diff --git a/intern/cycles/blender/curves.cpp b/intern/cycles/blender/curves.cpp
index f98719ff4f0..411eb16cd9d 100644
--- a/intern/cycles/blender/curves.cpp
+++ b/intern/cycles/blender/curves.cpp
@@ -803,6 +803,16 @@ static void attr_create_generic(Scene *scene,
             num_curves, num_keys, data, element, [&](int i) { return float(src[i]); });
         break;
       }
+      case BL::Attribute::data_type_INT32_2D: {
+        BL::Int2Attribute b_int2_attribute{b_attribute};
+        const int2 *src = static_cast<const int2 *>(b_int2_attribute.data[0].ptr.data);
+        Attribute *attr = attributes.add(name, TypeFloat2, element);
+        float2 *data = attr->data_float2();
+        fill_generic_attribute(num_curves, num_keys, data, element, [&](int i) {
+          return make_float2(float(src[i][0]), float(src[i][1]));
+        });
+        break;
+      }
       case BL::Attribute::data_type_FLOAT_VECTOR: {
         BL::FloatVectorAttribute b_vector_attribute{b_attribute};
         const float(*src)[3] = static_cast<const float(*)[3]>(b_vector_attribute.data[0].ptr.data);
diff --git a/intern/cycles/blender/mesh.cpp b/intern/cycles/blender/mesh.cpp
index 7e1b73ea40b..8692e84debe 100644
--- a/intern/cycles/blender/mesh.cpp
+++ b/intern/cycles/blender/mesh.cpp
@@ -528,6 +528,19 @@ static void attr_create_generic(Scene *scene,
         });
         break;
       }
+      case BL::Attribute::data_type_INT32_2D: {
+        BL::Int2Attribute b_int2_attribute{b_attribute};
+        if (b_int2_attribute.data.length() == 0) {
+          continue;
+        }
+        const int2 *src = static_cast<const int2 *>(b_int2_attribute.data[0].ptr.data);
+        Attribute *attr = attributes.add(name, TypeFloat2, element);
+        float2 *data = attr->data_float2();
+        fill_generic_attribute(b_mesh, data, b_domain, subdivision, [&](int i) {
+          return make_float2(float(src[i][0]), float(src[i][1]));
+        });
+        break;
+      }
       default:
         /* Not supported. */
         break;
diff --git a/intern/cycles/blender/pointcloud.cpp b/intern/cycles/blender/pointcloud.cpp
index f8b656ce688..32caebc0358 100644
--- a/intern/cycles/blender/pointcloud.cpp
+++ b/intern/cycles/blender/pointcloud.cpp
@@ -102,6 +102,16 @@ static void copy_attributes(PointCloud *pointcloud,
         }
         break;
       }
+      case BL::Attribute::data_type_INT32_2D: {
+        BL::Int2Attribute b_int2_attribute{b_attribute};
+        const int2 *src = static_cast<const int2 *>(b_int2_attribute.data[0].ptr.data);
+        Attribute *attr = attributes.add(name, TypeFloat2, element);
+        float2 *data = attr->data_float2();
+        for (int i = 0; i < num_points; i++) {
+          data[i] = make_float2(float(src[i][0]), float(src[i][1]));
+        }
+        break;
+      }
       case BL::Attribute::data_type_FLOAT_VECTOR: {
         BL::FloatVectorAttribute b_vector_attribute{b_attribute};
         const float(*src)[3] = static_cast<const float(*)[3]>(b_vector_attribute.data[0].ptr.data);
diff --git a/scripts/startup/bl_ui/space_toolsystem_toolbar.py b/scripts/startup/bl_ui/space_toolsystem_toolbar.py
index 93ab0392c66..6ea767433ea 100644
--- a/scripts/startup/bl_ui/space_toolsystem_toolbar.py
+++ b/scripts/startup/bl_ui/space_toolsystem_toolbar.py
@@ -31,21 +31,44 @@ def generate_from_enum_ex(
         type,
         attr,
         cursor='DEFAULT',
-        tooldef_keywords={},
-        exclude_filter={},
+        tooldef_keywords=None,
+        icon_map=None,
+        use_separators=True,
 ):
+    if tooldef_keywords is None:
+        tooldef_keywords = {}
+
     tool_defs = []
-    for enum in type.bl_rna.properties[attr].enum_items_static:
-        name = enum.name
-        idname = enum.identifier
-        if idname in exclude_filter:
-            continue
+
+    enum_items = getattr(
+        type.bl_rna.properties[attr],
+        "enum_items_static_ui" if use_separators else
+        "enum_items_static",
+    )
+
+    for enum in enum_items:
+        if use_separators:
+            if not (name := enum.name):
+                # Empty string for a UI Separator.
+                tool_defs.append(None)
+                continue
+            if not (idname := enum.identifier):
+                # This is a heading, there is no purpose in showing headings here.
+                continue
+        else:
+            name = enum.name
+            idname = enum.identifier
+
+        icon = icon_prefix + idname.lower()
+        if icon_map is not None:
+            icon = icon_map.get(icon, icon)
+
         tool_defs.append(
             ToolDef.from_dict(
                 dict(
                     idname=idname_prefix + name,
                     label=name,
-                    icon=icon_prefix + idname.lower(),
+                    icon=icon,
                     cursor=cursor,
                     data_block=idname,
                     **tooldef_keywords,
@@ -1316,6 +1339,9 @@ class _defs_sculpt:
             icon_prefix="brush.sculpt.",
             type=bpy.types.Brush,
             attr="sculpt_tool",
+            # TODO(@ideasman42): we may want to enable this,
+            # it causes awkward grouping with 2x column button layout.
+            use_separators=False,
         )
 
     @ToolDef.from_fn
@@ -2326,103 +2352,18 @@ class _defs_gpencil_weight:
 
 class _defs_curves_sculpt:
 
-    @ToolDef.from_fn
-    def selection_paint():
-        return dict(
-            idname="builtin_brush.selection_paint",
-            label="Selection Paint",
-            icon="ops.generic.select_paint",
-            data_block="SELECTION_PAINT",
-        )
-
-    @ToolDef.from_fn
-    def comb():
-        return dict(
-            idname="builtin_brush.comb",
-            label="Comb",
-            icon="ops.curves.sculpt_comb",
-            data_block='COMB',
-        )
-
-    @ToolDef.from_fn
-    def add():
-        return dict(
-            idname="builtin_brush.add",
-            label="Add",
-            icon="ops.curves.sculpt_add",
-            data_block='ADD',
-        )
-
-    @ToolDef.from_fn
-    def delete():
-        return dict(
-            idname="builtin_brush.delete",
-            label="Delete",
-            icon="ops.curves.sculpt_delete",
-            data_block='DELETE',
-        )
-
-    @ToolDef.from_fn
-    def snake_hook():
-        return dict(
-            idname="builtin_brush.snake_hook",
-            label="Snake Hook",
-            icon="ops.curves.sculpt_snake_hook",
-            data_block='SNAKE_HOOK',
-        )
-
-    @ToolDef.from_fn
-    def grow_shrink():
-        return dict(
-            idname="builtin_brush.grow_shrink",
-            label="Grow/Shrink",
-            icon="ops.curves.sculpt_grow_shrink",
-            data_block='GROW_SHRINK',
-        )
-
-    @ToolDef.from_fn
-    def pinch():
-        return dict(
-            idname="builtin_brush.pinch",
-            label="Pinch",
-            icon="ops.curves.sculpt_pinch",
-            data_block='PINCH',
-        )
-
-    @ToolDef.from_fn
-    def smooth():
-        return dict(
-            idname="builtin_brush.smooth",
-            label="Smooth",
-            icon="ops.curves.sculpt_smooth",
-            data_block='SMOOTH',
-        )
-
-    @ToolDef.from_fn
-    def puff():
-        return dict(
-            idname="builtin_brush.puff",
-            label="Puff",
-            icon="ops.curves.sculpt_puff",
-            data_block='PUFF',
-        )
-
-    @ToolDef.from_fn
-    def density():
-        return dict(
-            idname="builtin_brush.density",
-            label="Density",
-            icon="ops.curves.sculpt_density",
-            data_block="DENSITY",
-        )
-
-    @ToolDef.from_fn
-    def slide():
-        return dict(
-            idname="builtin_brush.slide",
-            label="Slide",
-            icon="ops.curves.sculpt_slide",
-            data_block="SLIDE",
+    @staticmethod
+    def generate_from_brushes(context):
+        return generate_from_enum_ex(
+            context,
+            idname_prefix="builtin_brush.",
+            icon_prefix="ops.curves.sculpt_",
+            type=bpy.types.Brush,
+            attr="curves_sculpt_tool",
+            icon_map={
+                # Use the generic icon for selection painting.
+                "ops.curves.sculpt_selection_paint": "ops.generic.select_paint",
+            },
         )
 
 
@@ -3193,19 +3134,7 @@ class VIEW3D_PT_tools_active(ToolSelectPanelHelper, Panel):
             ),
         ],
         'SCULPT_CURVES': [
-            _defs_curves_sculpt.selection_paint,
-            None,
-            _defs_curves_sculpt.add,
-            _defs_curves_sculpt.delete,
-            _defs_curves_sculpt.density,
-            None,
-            _defs_curves_sculpt.comb,
-            _defs_curves_sculpt.snake_hook,
-            _defs_curves_sculpt.grow_shrink,
-            _defs_curves_sculpt.pinch,
-            _defs_curves_sculpt.puff,
-            _defs_curves_sculpt.smooth,
-            _defs_curves_sculpt.slide,
+            _defs_curves_sculpt.generate_from_brushes,
             None,
             *_tools_annotate,
         ],
diff --git a/source/blender/CMakeLists.txt b/source/blender/CMakeLists.txt
index 9b0699e8f35..679496ee783 100644
--- a/source/blender/CMakeLists.txt
+++ b/source/blender/CMakeLists.txt
@@ -147,7 +147,7 @@ add_subdirectory(imbuf)
 add_subdirectory(imbuf/intern/oiio)
 add_subdirectory(nodes)
 add_subdirectory(modifiers)
-add_subdirectory(gpencil_modifiers)
+add_subdirectory(gpencil_modifiers_legacy)
 add_subdirectory(sequencer)
 add_subdirectory(shader_fx)
 add_subdirectory(io)
diff --git a/source/blender/blenkernel/BKE_attribute_math.hh b/source/blender/blenkernel/BKE_attribute_math.hh
index ef0744f21a6..8b576f4f586 100644
--- a/source/blender/blenkernel/BKE_attribute_math.hh
+++ b/source/blender/blenkernel/BKE_attribute_math.hh
@@ -23,6 +23,7 @@ inline void convert_to_static_type(const CPPType &cpp_type, const Func &func)
                               float2,
                               float3,
                               int,
+                              int2,
                               bool,
                               int8_t,
                               ColorGeometry4f,
@@ -68,6 +69,11 @@ template<> inline int mix2(const float factor, const int &a, const int &b)
   return int(std::round((1.0f - factor) * a + factor * b));
 }
 
+template<> inline int2 mix2(const float factor, const int2 &a, const int2 &b)
+{
+  return math::interpolate(a, b, factor);
+}
+
 template<> inline float mix2(const float factor, const float &a, const float &b)
 {
   return (1.0f - factor) * a + factor * b;
@@ -121,6 +127,11 @@ template<> inline int mix3(const float3 &weights, const int &v0, const int &v1,
   return int(std::round(weights.x * v0 + weights.y * v1 + weights.z * v2));
 }
 
+template<> inline int2 mix3(const float3 &weights, const int2 &v0, const int2 &v1, const int2 &v2)
+{
+  return int2(weights.x * float2(v0) + weights.y * float2(v1) + weights.z * float2(v2));
+}
+
 template<>
 inline float mix3(const float3 &weights, const float &v0, const float &v1, const float &v2)
 {
@@ -194,6 +205,14 @@ inline int mix4(const float4 &weights, const int &v0, const int &v1, const int &
   return int(std::round(weights.x * v0 + weights.y * v1 + weights.z * v2 + weights.w * v3));
 }
 
+template<>
+inline int2 mix4(
+    const float4 &weights, const int2 &v0, const int2 &v1, const int2 &v2, const int2 &v3)
+{
+  return int2(weights.x * float2(v0) + weights.y * float2(v1) + weights.z * float2(v2) +
+              weights.w * float2(v3));
+}
+
 template<>
 inline float mix4(
     const float4 &weights, const float &v0, const float &v1, const float &v2, const float &v3)
@@ -382,7 +401,7 @@ class SimpleMixerWithAccumulationType {
  private:
   struct Item {
     /* Store both values together, because they are accessed together. */
-    AccumulationT value = {0};
+    AccumulationT value = AccumulationT(0);
     float weight = 0.0f;
   };
 
@@ -517,6 +536,15 @@ template<> struct DefaultMixerStruct<int> {
    * uses double instead of float so that it is accurate for all 32 bit integers. */
   using type = SimpleMixerWithAccumulationType<int, double, double_to_int>;
 };
+template<> struct DefaultMixerStruct<int2> {
+  static int2 double_to_int(const double2 &value)
+  {
+    return int2(math::round(value));
+  }
+  /* Store interpolated ints in a double temporarily, so that weights are handled correctly. It
+   * uses double instead of float so that it is accurate for all 32 bit integers. */
+  using type = SimpleMixerWithAccumulationType<int2, double2, double_to_int>;
+};
 template<> struct DefaultMixerStruct<bool> {
   static bool float_to_bool(const float &value)
   {
diff --git a/source/blender/blenkernel/BKE_curves.hh b/source/blender/blenkernel/BKE_curves.hh
index 16b0c212a6c..7d24da5600c 100644
--- a/source/blender/blenkernel/BKE_curves.hh
+++ b/source/blender/blenkernel/BKE_curves.hh
@@ -9,6 +9,7 @@
 
 #include "BLI_bounds_types.hh"
 #include "BLI_generic_virtual_array.hh"
+#include "BLI_implicit_sharing.hh"
 #include "BLI_index_mask.hh"
 #include "BLI_math_matrix_types.hh"
 #include "BLI_math_vector_types.hh"
@@ -53,6 +54,9 @@ struct BasisCache {
  */
 class CurvesGeometryRuntime {
  public:
+  /** Implicit sharing user count for #CurvesGeometry::curve_offsets. */
+  ImplicitSharingInfo *curve_offsets_sharing_info = nullptr;
+
   /**
    * The cached number of curves with each type. Unlike other caches here, this is not computed
    * lazily, since it is needed so often and types are not adjusted much anyway.
diff --git a/source/blender/blenkernel/BKE_lib_query.h b/source/blender/blenkernel/BKE_lib_query.h
index d5023dd6e2b..7dcd25434b8 100644
--- a/source/blender/blenkernel/BKE_lib_query.h
+++ b/source/blender/blenkernel/BKE_lib_query.h
@@ -54,37 +54,45 @@ enum {
    * This means callback shall not *do* anything, only use this as informative data if it needs it.
    */
   IDWALK_CB_EMBEDDED = (1 << 4),
+  /**
+   * That ID pointer points to an embedded ID, but does not own it.
+   *
+   * E.g the `collection` pointer of the first ViewLayerCollection of a ViewLayer should always
+   * point to the scene's master collection, which is an embedded ID 'owned' by
+   * `Scene.master_collection`.
+   */
+  IDWALK_CB_EMBEDDED_NOT_OWNING = (1 << 5),
 
   /**
    * That ID is not really used by its owner, it's just an internal hint/helper.
    * This marks the 'from' pointers issue, like Key->from.
    * How to handle that kind of cases totally depends on what caller code is doing... */
-  IDWALK_CB_LOOPBACK = (1 << 5),
+  IDWALK_CB_LOOPBACK = (1 << 6),
 
   /** That ID is used as library override's reference by its owner. */
-  IDWALK_CB_OVERRIDE_LIBRARY_REFERENCE = (1 << 6),
+  IDWALK_CB_OVERRIDE_LIBRARY_REFERENCE = (1 << 7),
 
   /** That ID pointer is not overridable. */
-  IDWALK_CB_OVERRIDE_LIBRARY_NOT_OVERRIDABLE = (1 << 7),
+  IDWALK_CB_OVERRIDE_LIBRARY_NOT_OVERRIDABLE = (1 << 8),
 
   /**
    * Indicates that this is an internal runtime ID pointer, like e.g. `ID.newid` or `ID.original`.
    * \note Those should be ignored in most cases, and won't be processed/generated anyway unless
    * `IDWALK_DO_INTERNAL_RUNTIME_POINTERS` option is enabled.
    */
-  IDWALK_CB_INTERNAL = (1 << 8),
+  IDWALK_CB_INTERNAL = (1 << 9),
 
   /**
    * This ID usage is fully refcounted.
    * Callback is responsible to deal accordingly with #ID.us if needed.
    */
-  IDWALK_CB_USER = (1 << 9),
+  IDWALK_CB_USER = (1 << 10),
   /**
    * This ID usage is not refcounted, but at least one user should be generated by it (to avoid
    * e.g. losing the used ID on save/reload).
    * Callback is responsible to deal accordingly with #ID.us if needed.
    */
-  IDWALK_CB_USER_ONE = (1 << 10),
+  IDWALK_CB_USER_ONE = (1 << 11),
 };
 
 enum {
@@ -123,7 +131,9 @@ typedef int (*LibraryIDLinkCallback)(LibraryIDLinkCallbackData *cb_data);
 /* Flags for the foreach function itself. */
 enum {
   IDWALK_NOP = 0,
-  /** The callback will never modify the ID pointers it processes. */
+  /** The callback will never modify the ID pointers it processes.
+   * WARNING: It is very important to pass this flag when valid, as it can lead to important
+   * optimizations and debug/assert code. */
   IDWALK_READONLY = (1 << 0),
   /** Recurse into 'descendant' IDs.
    * Each ID is only processed once. Order of ID processing is not guaranteed.
diff --git a/source/blender/blenkernel/BKE_lib_remap.h b/source/blender/blenkernel/BKE_lib_remap.h
index dc3335aa231..98a27ec6d56 100644
--- a/source/blender/blenkernel/BKE_lib_remap.h
+++ b/source/blender/blenkernel/BKE_lib_remap.h
@@ -56,28 +56,38 @@ enum {
    */
   ID_REMAP_FORCE_NEVER_NULL_USAGE = 1 << 3,
   /** Do not remap library override pointers. */
-  ID_REMAP_SKIP_OVERRIDE_LIBRARY = 1 << 5,
-  /** Don't touch the special user counts (use when the 'old' remapped ID remains in use):
-   * - Do not transfer 'fake user' status from old to new ID.
-   * - Do not clear 'extra user' from old ID. */
-  ID_REMAP_SKIP_USER_CLEAR = 1 << 6,
+  ID_REMAP_SKIP_OVERRIDE_LIBRARY = 1 << 4,
   /**
    * Force internal ID runtime pointers (like `ID.newid`, `ID.orig_id` etc.) to also be processed.
    * This should only be needed in some very specific cases, typically only BKE ID management code
    * should need it (e.g. required from `id_delete` to ensure no runtime pointer remains using
    * freed ones).
    */
-  ID_REMAP_FORCE_INTERNAL_RUNTIME_POINTERS = 1 << 7,
-  /** Force handling user count even for IDs that are outside of Main (used in some cases when
-   * dealing with IDs temporarily out of Main, but which will be put in it ultimately).
-   */
-  ID_REMAP_FORCE_USER_REFCOUNT = 1 << 8,
+  ID_REMAP_FORCE_INTERNAL_RUNTIME_POINTERS = 1 << 5,
+  /** Force remapping of 'UI-like' ID usages (ID pointers stored in editors data etc.). */
+  ID_REMAP_FORCE_UI_POINTERS = 1 << 6,
   /**
    * Force obdata pointers to also be processed, even when object (`id_owner`) is in Edit mode.
    * This is required by some tools creating/deleting IDs while operating in Edit mode, like e.g.
    * the 'separate' mesh operator.
    */
-  ID_REMAP_FORCE_OBDATA_IN_EDITMODE = 1 << 9,
+  ID_REMAP_FORCE_OBDATA_IN_EDITMODE = 1 << 7,
+
+  /** Don't touch the special user counts (use when the 'old' remapped ID remains in use):
+   * - Do not transfer 'fake user' status from old to new ID.
+   * - Do not clear 'extra user' from old ID. */
+  ID_REMAP_SKIP_USER_CLEAR = 1 << 16,
+  /** Force handling user count even for IDs that are outside of Main (used in some cases when
+   * dealing with IDs temporarily out of Main, but which will be put in it ultimately).
+   */
+  ID_REMAP_FORCE_USER_REFCOUNT = 1 << 17,
+  /** Do NOT handle user count for IDs (used in some cases when dealing with IDs from different
+   * BMains, if usercount will be recomputed anyway afterwards, like e.g. in memfile reading during
+   * undo step decoding). */
+  ID_REMAP_SKIP_USER_REFCOUNT = 1 << 18,
+  /** Do NOT tag IDs which had some of their ID pointers updated for update in the depsgraph, or ID
+   * type specific updates, like e.g. with node trees. */
+  ID_REMAP_SKIP_UPDATE_TAGGING = 1 << 19,
 };
 
 typedef enum eIDRemapType {
@@ -95,12 +105,24 @@ typedef enum eIDRemapType {
  */
 void BKE_libblock_remap_multiple_locked(struct Main *bmain,
                                         struct IDRemapper *mappings,
-                                        short remap_flags);
+                                        const int remap_flags);
 
 void BKE_libblock_remap_multiple(struct Main *bmain,
                                  struct IDRemapper *mappings,
-                                 short remap_flags);
+                                 const int remap_flags);
 
+/**
+ * Bare raw remapping of IDs, with no other processing than actually updating the ID pointers. No
+ * usercount, direct vs indirect linked status update, depsgraph tagging, etc.
+ *
+ * This is way more efficient than regular remapping from #BKE_libblock_remap_multiple & co, but it
+ * implies that calling code handles all the other aspects described above. This is typically the
+ * case e.g. in readfile process.
+ *
+ * WARNING: This call will likely leave the given BMain in invalid state in many aspects. */
+void BKE_libblock_remap_multiple_raw(struct Main *bmain,
+                                     struct IDRemapper *mappings,
+                                     const int remap_flags);
 /**
  * Replace all references in given Main to \a old_id by \a new_id
  * (if \a new_id is NULL, it unlinks \a old_id).
@@ -108,9 +130,9 @@ void BKE_libblock_remap_multiple(struct Main *bmain,
  * \note Requiring new_id to be non-null, this *may* not be the case ultimately,
  * but makes things simpler for now.
  */
-void BKE_libblock_remap_locked(struct Main *bmain, void *old_idv, void *new_idv, short remap_flags)
+void BKE_libblock_remap_locked(struct Main *bmain, void *old_idv, void *new_idv, int remap_flags)
     ATTR_NONNULL(1, 2);
-void BKE_libblock_remap(struct Main *bmain, void *old_idv, void *new_idv, short remap_flags)
+void BKE_libblock_remap(struct Main *bmain, void *old_idv, void *new_idv, int remap_flags)
     ATTR_NONNULL(1, 2);
 
 /**
@@ -130,12 +152,12 @@ void BKE_libblock_unlink(struct Main *bmain,
  *
  * \param old_idv: Unlike BKE_libblock_remap, can be NULL,
  * in which case all ID usages by given \a idv will be cleared.
+ *
+ * \param bmain: May be NULL, in which case there won't be depsgraph updates nor post-processing on
+ * some ID types (like collections or objects) to ensure their runtime data is valid.
  */
-void BKE_libblock_relink_ex(struct Main *bmain,
-                            void *idv,
-                            void *old_idv,
-                            void *new_idv,
-                            short remap_flags) ATTR_NONNULL(1, 2);
+void BKE_libblock_relink_ex(
+    struct Main *bmain, void *idv, void *old_idv, void *new_idv, int remap_flags) ATTR_NONNULL(2);
 /**
  * Same as #BKE_libblock_relink_ex, but applies all rules defined in \a id_remapper to \a ids (or
  * does cleanup if `ID_REMAP_TYPE_CLEANUP` is specified as \a remap_type).
@@ -144,7 +166,7 @@ void BKE_libblock_relink_multiple(struct Main *bmain,
                                   struct LinkNode *ids,
                                   eIDRemapType remap_type,
                                   struct IDRemapper *id_remapper,
-                                  short remap_flags);
+                                  int remap_flags);
 
 /**
  * Remaps ID usages of given ID to their `id->newid` pointer if not None, and proceeds recursively
diff --git a/source/blender/blenkernel/BKE_mesh.h b/source/blender/blenkernel/BKE_mesh.h
index 4e670d8e2b6..6c6afce56f2 100644
--- a/source/blender/blenkernel/BKE_mesh.h
+++ b/source/blender/blenkernel/BKE_mesh.h
@@ -800,10 +800,7 @@ BLI_INLINE const int *BKE_mesh_poly_offsets(const Mesh *mesh)
 {
   return mesh->poly_offset_indices;
 }
-BLI_INLINE int *BKE_mesh_poly_offsets_for_write(Mesh *mesh)
-{
-  return mesh->poly_offset_indices;
-}
+int *BKE_mesh_poly_offsets_for_write(Mesh *mesh);
 
 BLI_INLINE const int *BKE_mesh_corner_verts(const Mesh *mesh)
 {
diff --git a/source/blender/blenkernel/BKE_mesh_types.h b/source/blender/blenkernel/BKE_mesh_types.h
index 21ccc8f7da0..2d4788bd1d7 100644
--- a/source/blender/blenkernel/BKE_mesh_types.h
+++ b/source/blender/blenkernel/BKE_mesh_types.h
@@ -16,6 +16,7 @@
 #  include "BLI_array.hh"
 #  include "BLI_bit_vector.hh"
 #  include "BLI_bounds_types.hh"
+#  include "BLI_implicit_sharing.hh"
 #  include "BLI_math_vector_types.hh"
 #  include "BLI_shared_cache.hh"
 #  include "BLI_span.hh"
@@ -96,6 +97,9 @@ struct MeshRuntime {
   /** Needed to ensure some thread-safety during render data pre-processing. */
   std::mutex render_mutex;
 
+  /** Implicit sharing user count for #Mesh::poly_offset_indices. */
+  ImplicitSharingInfoHandle *poly_offsets_sharing_info;
+
   /**
    * A cache of bounds shared between data-blocks with unchanged positions. When changing positions
    * affect the bounds, the cache is "un-shared" with other geometries. See #SharedCache comments.
diff --git a/source/blender/blenkernel/CMakeLists.txt b/source/blender/blenkernel/CMakeLists.txt
index 9dd11437dd2..66562ef0702 100644
--- a/source/blender/blenkernel/CMakeLists.txt
+++ b/source/blender/blenkernel/CMakeLists.txt
@@ -12,7 +12,7 @@ set(INC
   ../depsgraph
   ../draw
   ../functions
-  ../gpencil_modifiers
+  ../gpencil_modifiers_legacy
   ../gpu
   ../ikplugin
   ../imbuf
@@ -525,7 +525,7 @@ set(LIB
   bf_depsgraph
   bf_draw
   bf_functions
-  bf_gpencil_modifiers
+  bf_gpencil_modifiers_legacy
   bf_gpu
   bf_ikplugin
   bf_imbuf
diff --git a/source/blender/blenkernel/intern/attribute_access.cc b/source/blender/blenkernel/intern/attribute_access.cc
index 55739083f1e..f016ed52fe7 100644
--- a/source/blender/blenkernel/intern/attribute_access.cc
+++ b/source/blender/blenkernel/intern/attribute_access.cc
@@ -92,17 +92,19 @@ static int attribute_data_type_complexity(const eCustomDataType data_type)
       return 2;
     case CD_PROP_FLOAT:
       return 3;
-    case CD_PROP_FLOAT2:
+    case CD_PROP_INT32_2D:
       return 4;
-    case CD_PROP_FLOAT3:
+    case CD_PROP_FLOAT2:
       return 5;
-    case CD_PROP_BYTE_COLOR:
+    case CD_PROP_FLOAT3:
       return 6;
-    case CD_PROP_COLOR:
+    case CD_PROP_BYTE_COLOR:
       return 7;
+    case CD_PROP_COLOR:
+      return 8;
 #if 0 /* These attribute types are not supported yet. */
     case CD_PROP_STRING:
-      return 6;
+      return 9;
 #endif
     default:
       /* Only accept "generic" custom data types used by the attribute system. */
diff --git a/source/blender/blenkernel/intern/blendfile_link_append.c b/source/blender/blenkernel/intern/blendfile_link_append.c
index c5d77a517dc..7fe9f514e2a 100644
--- a/source/blender/blenkernel/intern/blendfile_link_append.c
+++ b/source/blender/blenkernel/intern/blendfile_link_append.c
@@ -923,8 +923,8 @@ static int foreach_libblock_link_append_callback(LibraryIDLinkCallbackData *cb_d
 {
   /* NOTE: It is important to also skip liboverride references here, as those should never be made
    * local. */
-  if (cb_data->cb_flag & (IDWALK_CB_EMBEDDED | IDWALK_CB_INTERNAL | IDWALK_CB_LOOPBACK |
-                          IDWALK_CB_OVERRIDE_LIBRARY_REFERENCE)) {
+  if (cb_data->cb_flag & (IDWALK_CB_EMBEDDED | IDWALK_CB_EMBEDDED_NOT_OWNING | IDWALK_CB_INTERNAL |
+                          IDWALK_CB_LOOPBACK | IDWALK_CB_OVERRIDE_LIBRARY_REFERENCE)) {
     return IDWALK_RET_NOP;
   }
 
@@ -1426,7 +1426,7 @@ static void blendfile_library_relocate_remap(Main *bmain,
                                              ID *new_id,
                                              ReportList *reports,
                                              const bool do_reload,
-                                             const short remap_flags)
+                                             const int remap_flags)
 {
   BLI_assert(old_id);
   if (do_reload) {
@@ -1594,8 +1594,8 @@ void BKE_blendfile_library_relocate(BlendfileLinkAppendContext *lapp_context,
 
   BKE_layer_collection_resync_forbid();
   /* Note that in reload case, we also want to replace indirect usages. */
-  const short remap_flags = ID_REMAP_SKIP_NEVER_NULL_USAGE |
-                            (do_reload ? 0 : ID_REMAP_SKIP_INDIRECT_USAGE);
+  const int remap_flags = ID_REMAP_SKIP_NEVER_NULL_USAGE |
+                          (do_reload ? 0 : ID_REMAP_SKIP_INDIRECT_USAGE);
   for (item_idx = 0, itemlink = lapp_context->items.list; itemlink;
        item_idx++, itemlink = itemlink->next) {
     BlendfileLinkAppendContextItem *item = itemlink->link;
diff --git a/source/blender/blenkernel/intern/curves_geometry.cc b/source/blender/blenkernel/intern/curves_geometry.cc
index 4222be8ce8a..9f8ab69be98 100644
--- a/source/blender/blenkernel/intern/curves_geometry.cc
+++ b/source/blender/blenkernel/intern/curves_geometry.cc
@@ -60,13 +60,24 @@ CurvesGeometry::CurvesGeometry(const int point_num, const int curve_num)
   CustomData_add_layer_named(
       &this->point_data, CD_PROP_FLOAT3, CD_CONSTRUCT, this->point_num, ATTR_POSITION.c_str());
 
-  this->curve_offsets = (int *)MEM_malloc_arrayN(this->curve_num + 1, sizeof(int), __func__);
-#ifdef DEBUG
-  this->offsets_for_write().fill(-1);
-#endif
-  this->offsets_for_write().first() = 0;
-
   this->runtime = MEM_new<CurvesGeometryRuntime>(__func__);
+
+  if (curve_num > 0) {
+    this->curve_offsets = static_cast<int *>(
+        MEM_malloc_arrayN(this->curve_num + 1, sizeof(int), __func__));
+    this->runtime->curve_offsets_sharing_info = implicit_sharing::info_for_mem_free(
+        this->curve_offsets);
+#ifdef DEBUG
+    this->offsets_for_write().fill(-1);
+#endif
+    /* Set common values for convenience. */
+    this->curve_offsets[0] = 0;
+    this->curve_offsets[this->curve_num] = this->point_num;
+  }
+  else {
+    this->curve_offsets = nullptr;
+  }
+
   /* Fill the type counts with the default so they're in a valid state. */
   this->runtime->type_counts[CURVE_TYPE_CATMULL_ROM] = curve_num;
 }
@@ -83,9 +94,10 @@ static void copy_curves_geometry(CurvesGeometry &dst, const CurvesGeometry &src)
   CustomData_copy(&src.point_data, &dst.point_data, CD_MASK_ALL, dst.point_num);
   CustomData_copy(&src.curve_data, &dst.curve_data, CD_MASK_ALL, dst.curve_num);
 
-  MEM_SAFE_FREE(dst.curve_offsets);
-  dst.curve_offsets = (int *)MEM_malloc_arrayN(dst.point_num + 1, sizeof(int), __func__);
-  dst.offsets_for_write().copy_from(src.offsets());
+  implicit_sharing::copy_shared_pointer(src.curve_offsets,
+                                        src.runtime->curve_offsets_sharing_info,
+                                        &dst.curve_offsets,
+                                        &dst.runtime->curve_offsets_sharing_info);
 
   dst.tag_topology_changed();
 
@@ -127,7 +139,6 @@ static void move_curves_geometry(CurvesGeometry &dst, CurvesGeometry &src)
   src.curve_num = 0;
 
   std::swap(dst.curve_offsets, src.curve_offsets);
-  MEM_SAFE_FREE(src.curve_offsets);
 
   std::swap(dst.runtime, src.runtime);
 }
@@ -149,7 +160,8 @@ CurvesGeometry::~CurvesGeometry()
 {
   CustomData_free(&this->point_data, this->point_num);
   CustomData_free(&this->curve_data, this->curve_num);
-  MEM_SAFE_FREE(this->curve_offsets);
+  implicit_sharing::free_shared_data(&this->curve_offsets,
+                                     &this->runtime->curve_offsets_sharing_info);
   MEM_delete(this->runtime);
   this->runtime = nullptr;
 }
@@ -326,6 +338,8 @@ Span<int> CurvesGeometry::offsets() const
 }
 MutableSpan<int> CurvesGeometry::offsets_for_write()
 {
+  implicit_sharing::make_trivial_data_mutable(
+      &this->curve_offsets, &this->runtime->curve_offsets_sharing_info, this->curve_num + 1);
   return {this->curve_offsets, this->curve_num + 1};
 }
 
@@ -948,8 +962,14 @@ void CurvesGeometry::resize(const int points_num, const int curves_num)
   }
   if (curves_num != this->curve_num) {
     CustomData_realloc(&this->curve_data, this->curves_num(), curves_num);
+    implicit_sharing::resize_trivial_array(&this->curve_offsets,
+                                           &this->runtime->curve_offsets_sharing_info,
+                                           this->curve_num == 0 ? 0 : (this->curve_num + 1),
+                                           curves_num + 1);
+    /* Set common values for convenience. */
+    this->curve_offsets[0] = 0;
+    this->curve_offsets[curves_num] = this->point_num;
     this->curve_num = curves_num;
-    this->curve_offsets = (int *)MEM_reallocN(this->curve_offsets, sizeof(int) * (curves_num + 1));
   }
   this->tag_topology_changed();
 }
@@ -1585,7 +1605,11 @@ void CurvesGeometry::blend_read(BlendDataReader &reader)
   CustomData_blend_read(&reader, &this->point_data, this->point_num);
   CustomData_blend_read(&reader, &this->curve_data, this->curve_num);
 
-  BLO_read_int32_array(&reader, this->curve_num + 1, &this->curve_offsets);
+  if (this->curve_offsets) {
+    BLO_read_int32_array(&reader, this->curve_num + 1, &this->curve_offsets);
+    this->runtime->curve_offsets_sharing_info = implicit_sharing::info_for_mem_free(
+        this->curve_offsets);
+  }
 
   /* Recalculate curve type count cache that isn't saved in files. */
   this->update_curve_types();
diff --git a/source/blender/blenkernel/intern/customdata.cc b/source/blender/blenkernel/intern/customdata.cc
index 28ae7bfa145..eda5e0482c0 100644
--- a/source/blender/blenkernel/intern/customdata.cc
+++ b/source/blender/blenkernel/intern/customdata.cc
@@ -1892,8 +1892,8 @@ static const LayerTypeInfo LAYERTYPEINFO[CD_NUMTYPES] = {
     {sizeof(float), "MFloatProperty", 1, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr},
     /* 45: CD_PROP_INT8 */
     {sizeof(int8_t), "MInt8Property", 1, N_("Int8"), nullptr, nullptr, nullptr, nullptr, nullptr},
-    /* 46: CD_HAIRMAPPING */ /* UNUSED */
-    {-1, "", 1, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr},
+    /* 46: CD_PROP_INT32_2D */
+    {sizeof(vec2i), "vec2i", 1, N_("Int 2D"), nullptr, nullptr, nullptr, nullptr, nullptr},
     /* 47: CD_PROP_COLOR */
     {sizeof(MPropCol),
      "MPropCol",
@@ -5360,6 +5360,8 @@ const blender::CPPType *custom_data_type_to_cpp_type(const eCustomDataType type)
       return &CPPType::get<float3>();
     case CD_PROP_INT32:
       return &CPPType::get<int>();
+    case CD_PROP_INT32_2D:
+      return &CPPType::get<int2>();
     case CD_PROP_COLOR:
       return &CPPType::get<ColorGeometry4f>();
     case CD_PROP_BOOL:
@@ -5389,6 +5391,9 @@ eCustomDataType cpp_type_to_custom_data_type(const blender::CPPType &type)
   if (type.is<int>()) {
     return CD_PROP_INT32;
   }
+  if (type.is<int2>()) {
+    return CD_PROP_INT32_2D;
+  }
   if (type.is<ColorGeometry4f>()) {
     return CD_PROP_COLOR;
   }
diff --git a/source/blender/blenkernel/intern/gpencil_geom_legacy.cc b/source/blender/blenkernel/intern/gpencil_geom_legacy.cc
index 13f70cbf1bd..a502ca8f174 100644
--- a/source/blender/blenkernel/intern/gpencil_geom_legacy.cc
+++ b/source/blender/blenkernel/intern/gpencil_geom_legacy.cc
@@ -649,7 +649,7 @@ bool BKE_gpencil_stroke_stretch(bGPDstroke *gps,
   if (!isfinite(used_percent_length)) {
     /* #used_percent_length must always be finite, otherwise a segfault occurs.
      * Since this function should never segfault, set #used_percent_length to a safe fallback. */
-    /* NOTE: This fallback is used if gps->totpoints == 2, see MOD_gpencillength.c */
+    /* NOTE: This fallback is used if gps->totpoints == 2, see MOD_gpencil_legacy_length.c */
     used_percent_length = 0.1f;
   }
 
diff --git a/source/blender/blenkernel/intern/gpencil_modifier_legacy.c b/source/blender/blenkernel/intern/gpencil_modifier_legacy.c
index b9977f637bb..0fe854a7c3b 100644
--- a/source/blender/blenkernel/intern/gpencil_modifier_legacy.c
+++ b/source/blender/blenkernel/intern/gpencil_modifier_legacy.c
@@ -43,8 +43,8 @@
 #include "DEG_depsgraph.h"
 #include "DEG_depsgraph_query.h"
 
-#include "MOD_gpencil_lineart.h"
-#include "MOD_gpencil_modifiertypes.h"
+#include "MOD_gpencil_legacy_lineart.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
 
 #include "BLO_read_write.h"
 
@@ -329,7 +329,7 @@ void BKE_gpencil_frame_active_set(Depsgraph *depsgraph, bGPdata *gpd)
 void BKE_gpencil_modifier_init(void)
 {
   /* Initialize modifier types */
-  gpencil_modifier_type_init(modifier_gpencil_types); /* MOD_gpencil_util.c */
+  gpencil_modifier_type_init(modifier_gpencil_types); /* MOD_gpencil_legacy_util.c */
 
 #if 0
   /* Note that GPencil actually does not support these at the moment,
diff --git a/source/blender/blenkernel/intern/lib_id.c b/source/blender/blenkernel/intern/lib_id.c
index 757d2390f22..0d9ff62a2ed 100644
--- a/source/blender/blenkernel/intern/lib_id.c
+++ b/source/blender/blenkernel/intern/lib_id.c
@@ -404,7 +404,7 @@ static int lib_id_expand_local_cb(LibraryIDLinkCallbackData *cb_data)
     return IDWALK_RET_NOP;
   }
 
-  if (cb_flag & IDWALK_CB_EMBEDDED) {
+  if (cb_flag & (IDWALK_CB_EMBEDDED | IDWALK_CB_EMBEDDED_NOT_OWNING)) {
     /* Embedded data-blocks need to be made fully local as well.
      * Note however that in some cases (when owner ID had to be duplicated instead of being made
      * local directly), its embedded IDs should also have already been duplicated, and hence be
@@ -1494,12 +1494,11 @@ bool BKE_id_new_name_validate(
     return result;
   }
 
-  /* if no name given, use name of current ID
-   * else make a copy (tname args can be const) */
+  /* If no name given, use name of current ID. */
   if (tname == NULL) {
     tname = id->name + 2;
   }
-
+  /* Make a copy of given name (tname args can be const). */
   BLI_strncpy(name, tname, sizeof(name));
 
   if (name[0] == '\0') {
diff --git a/source/blender/blenkernel/intern/lib_query.c b/source/blender/blenkernel/intern/lib_query.c
index 2b6a4a7f4aa..a32ea01ce2a 100644
--- a/source/blender/blenkernel/intern/lib_query.c
+++ b/source/blender/blenkernel/intern/lib_query.c
@@ -696,7 +696,8 @@ static void lib_query_unused_ids_tag_recurse(Main *bmain,
 
   /* An ID user is 'valid' (i.e. may affect the 'used'/'not used' status of the ID it uses) if it
    * does not match `ignored_usages`, and does match `required_usages`. */
-  const int ignored_usages = (IDWALK_CB_LOOPBACK | IDWALK_CB_EMBEDDED);
+  const int ignored_usages = (IDWALK_CB_LOOPBACK | IDWALK_CB_EMBEDDED |
+                              IDWALK_CB_EMBEDDED_NOT_OWNING);
   const int required_usages = (IDWALK_CB_USER | IDWALK_CB_USER_ONE);
 
   /* This ID may be tagged as unused if none of its users are 'valid', as defined above.
diff --git a/source/blender/blenkernel/intern/lib_remap.c b/source/blender/blenkernel/intern/lib_remap.c
index 7376ea3f39a..857ad6f1e6e 100644
--- a/source/blender/blenkernel/intern/lib_remap.c
+++ b/source/blender/blenkernel/intern/lib_remap.c
@@ -60,7 +60,7 @@ typedef struct IDRemap {
 
   /** The ID in which we are replacing old_id by new_id usages. */
   ID *id_owner;
-  short flag;
+  int flag;
 } IDRemap;
 
 /* IDRemap->flag enums defined in BKE_lib.h */
@@ -104,30 +104,46 @@ static void foreach_libblock_remap_callback_apply(ID *id_owner,
                                                   const IDRemapperApplyOptions id_remapper_options,
                                                   const int cb_flag,
                                                   const bool is_indirect,
-                                                  const bool violates_never_null,
-                                                  const bool force_user_refcount)
+                                                  const bool violates_never_null)
 {
+  const bool skip_update_tagging = (id_remap_data->flag & ID_REMAP_SKIP_UPDATE_TAGGING) != 0;
+  const bool skip_user_refcount = (id_remap_data->flag & ID_REMAP_SKIP_USER_REFCOUNT) != 0;
+  const bool force_user_refcount = (id_remap_data->flag & ID_REMAP_FORCE_USER_REFCOUNT) != 0;
+  BLI_assert(!skip_user_refcount || !force_user_refcount);
+
   ID *old_id = *id_ptr;
   if (!violates_never_null) {
     BKE_id_remapper_apply_ex(mappings, id_ptr, id_remapper_options, id_self);
-    DEG_id_tag_update_ex(id_remap_data->bmain,
-                         id_self,
-                         ID_RECALC_COPY_ON_WRITE | ID_RECALC_TRANSFORM | ID_RECALC_GEOMETRY);
-    if (id_self != id_owner) {
-      DEG_id_tag_update_ex(id_remap_data->bmain,
-                           id_owner,
-                           ID_RECALC_COPY_ON_WRITE | ID_RECALC_TRANSFORM | ID_RECALC_GEOMETRY);
-    }
-    if (GS(id_owner->name) == ID_NT) {
-      /* Make sure that the node tree is updated after a property in it changed. Ideally, we would
-       * know which nodes property was changed so that only this node is tagged. */
-      BKE_ntree_update_tag_all((bNodeTree *)id_owner);
+    if (!skip_update_tagging) {
+      if (id_remap_data->bmain != NULL) {
+        DEG_id_tag_update_ex(id_remap_data->bmain,
+                             id_self,
+                             ID_RECALC_COPY_ON_WRITE | ID_RECALC_TRANSFORM | ID_RECALC_GEOMETRY);
+        if (id_self != id_owner) {
+          DEG_id_tag_update_ex(id_remap_data->bmain,
+                               id_owner,
+                               ID_RECALC_COPY_ON_WRITE | ID_RECALC_TRANSFORM | ID_RECALC_GEOMETRY);
+        }
+      }
+      if (GS(id_owner->name) == ID_NT) {
+        /* Make sure that the node tree is updated after a property in it changed. Ideally, we
+         * would know which nodes property was changed so that only this node is tagged. */
+        BKE_ntree_update_tag_all((bNodeTree *)id_owner);
+      }
     }
   }
   /* Get the new_id pointer. When the mapping is violating never null we should use a NULL
    * pointer otherwise the incorrect users are decreased and increased on the same instance. */
   ID *new_id = violates_never_null ? NULL : *id_ptr;
 
+  if (!is_indirect && new_id) {
+    new_id->runtime.remap.status |= ID_REMAP_IS_LINKED_DIRECT;
+  }
+
+  if (skip_user_refcount) {
+    return;
+  }
+
   if (cb_flag & IDWALK_CB_USER) {
     /* NOTE: by default we don't user-count IDs which are not in the main database.
      * This is because in certain conditions we can have data-blocks in
@@ -148,16 +164,13 @@ static void foreach_libblock_remap_callback_apply(ID *id_owner,
     /* We cannot affect old_id->us directly, LIB_TAG_EXTRAUSER(_SET)
      * are assumed to be set as needed, that extra user is processed in final handling. */
   }
-  if (!is_indirect && new_id) {
-    new_id->runtime.remap.status |= ID_REMAP_IS_LINKED_DIRECT;
-  }
 }
 
 static int foreach_libblock_remap_callback(LibraryIDLinkCallbackData *cb_data)
 {
   const int cb_flag = cb_data->cb_flag;
 
-  if (cb_flag & IDWALK_CB_EMBEDDED) {
+  if (cb_flag & (IDWALK_CB_EMBEDDED | IDWALK_CB_EMBEDDED_NOT_OWNING)) {
     return IDWALK_RET_NOP;
   }
 
@@ -218,7 +231,6 @@ static int foreach_libblock_remap_callback(LibraryIDLinkCallbackData *cb_data)
                                     (id_remap_data->flag & ID_REMAP_FORCE_NEVER_NULL_USAGE) == 0);
   const bool skip_reference = (id_remap_data->flag & ID_REMAP_SKIP_OVERRIDE_LIBRARY) != 0;
   const bool skip_never_null = (id_remap_data->flag & ID_REMAP_SKIP_NEVER_NULL_USAGE) != 0;
-  const bool force_user_refcount = (id_remap_data->flag & ID_REMAP_FORCE_USER_REFCOUNT) != 0;
 
 #ifdef DEBUG_PRINT
   printf(
@@ -264,8 +276,7 @@ static int foreach_libblock_remap_callback(LibraryIDLinkCallbackData *cb_data)
                                           id_remapper_options,
                                           cb_flag,
                                           is_indirect,
-                                          violates_never_null,
-                                          force_user_refcount);
+                                          violates_never_null);
   }
 
   return IDWALK_RET_NOP;
@@ -449,7 +460,8 @@ static void libblock_remap_reset_remapping_status_callback(ID *old_id,
  *     (i.e. \a id does not references any other data-block anymore).
  *   + If \a old_id is non-NULL, behavior is as with a NULL \a id, but only within given \a id.
  *
- * \param bmain: the Main data storage to operate on (must never be NULL).
+ * \param bmain: the Main data storage to operate on (may be NULL, in which case part of the
+ * post-process/depsgraph update won't happen).
  * \param id: the data-block to operate on
  * (can be NULL, in which case we operate over all IDs from given bmain).
  * \param old_id: the data-block to dereference (may be NULL if \a id is non-NULL).
@@ -457,17 +469,18 @@ static void libblock_remap_reset_remapping_status_callback(ID *old_id,
  * \param r_id_remap_data: if non-NULL, the IDRemap struct to use
  * (useful to retrieve info about remapping process).
  */
-ATTR_NONNULL(1)
 static void libblock_remap_data(Main *bmain,
                                 ID *id,
                                 eIDRemapType remap_type,
                                 struct IDRemapper *id_remapper,
-                                const short remap_flags)
+                                const int remap_flags)
 {
   IDRemap id_remap_data = {0};
-  const int foreach_id_flags = ((remap_flags & ID_REMAP_FORCE_INTERNAL_RUNTIME_POINTERS) != 0 ?
-                                    IDWALK_DO_INTERNAL_RUNTIME_POINTERS :
-                                    IDWALK_NOP);
+  const int foreach_id_flags =
+      (((remap_flags & ID_REMAP_FORCE_INTERNAL_RUNTIME_POINTERS) != 0 ?
+            IDWALK_DO_INTERNAL_RUNTIME_POINTERS :
+            IDWALK_NOP) |
+       ((remap_flags & ID_REMAP_FORCE_UI_POINTERS) != 0 ? IDWALK_INCLUDE_UI : IDWALK_NOP));
 
   id_remap_data.id_remapper = id_remapper;
   id_remap_data.type = remap_type;
@@ -519,7 +532,7 @@ static void libblock_remap_data(Main *bmain,
 
 typedef struct LibblockRemapMultipleUserData {
   Main *bmain;
-  short remap_flags;
+  int remap_flags;
 } LibBlockRemapMultipleUserData;
 
 static void libblock_remap_foreach_idpair_cb(ID *old_id, ID *new_id, void *user_data)
@@ -530,7 +543,7 @@ static void libblock_remap_foreach_idpair_cb(ID *old_id, ID *new_id, void *user_
 
   LibBlockRemapMultipleUserData *data = user_data;
   Main *bmain = data->bmain;
-  const short remap_flags = data->remap_flags;
+  const int remap_flags = data->remap_flags;
 
   BLI_assert(old_id != NULL);
   BLI_assert((new_id == NULL) || GS(old_id->name) == GS(new_id->name));
@@ -614,7 +627,7 @@ static void libblock_remap_foreach_idpair_cb(ID *old_id, ID *new_id, void *user_
 
 void BKE_libblock_remap_multiple_locked(Main *bmain,
                                         struct IDRemapper *mappings,
-                                        const short remap_flags)
+                                        const int remap_flags)
 {
   if (BKE_id_remapper_is_empty(mappings)) {
     /* Early exit nothing to do. */
@@ -640,7 +653,23 @@ void BKE_libblock_remap_multiple_locked(Main *bmain,
   DEG_relations_tag_update(bmain);
 }
 
-void BKE_libblock_remap_locked(Main *bmain, void *old_idv, void *new_idv, const short remap_flags)
+void BKE_libblock_remap_multiple_raw(Main *bmain,
+                                     struct IDRemapper *mappings,
+                                     const int remap_flags)
+{
+  if (BKE_id_remapper_is_empty(mappings)) {
+    /* Early exit nothing to do. */
+    return;
+  }
+
+  libblock_remap_data(bmain,
+                      NULL,
+                      ID_REMAP_TYPE_REMAP,
+                      mappings,
+                      remap_flags | ID_REMAP_SKIP_USER_REFCOUNT | ID_REMAP_SKIP_UPDATE_TAGGING);
+}
+
+void BKE_libblock_remap_locked(Main *bmain, void *old_idv, void *new_idv, const int remap_flags)
 {
   struct IDRemapper *remapper = BKE_id_remapper_create();
   ID *old_id = old_idv;
@@ -650,7 +679,7 @@ void BKE_libblock_remap_locked(Main *bmain, void *old_idv, void *new_idv, const
   BKE_id_remapper_free(remapper);
 }
 
-void BKE_libblock_remap(Main *bmain, void *old_idv, void *new_idv, const short remap_flags)
+void BKE_libblock_remap(Main *bmain, void *old_idv, void *new_idv, const int remap_flags)
 {
   BKE_main_lock(bmain);
 
@@ -659,7 +688,7 @@ void BKE_libblock_remap(Main *bmain, void *old_idv, void *new_idv, const short r
   BKE_main_unlock(bmain);
 }
 
-void BKE_libblock_remap_multiple(Main *bmain, struct IDRemapper *mappings, const short remap_flags)
+void BKE_libblock_remap_multiple(Main *bmain, struct IDRemapper *mappings, const int remap_flags)
 {
   BKE_main_lock(bmain);
 
@@ -673,8 +702,8 @@ void BKE_libblock_unlink(Main *bmain,
                          const bool do_flag_never_null,
                          const bool do_skip_indirect)
 {
-  const short remap_flags = (do_skip_indirect ? ID_REMAP_SKIP_INDIRECT_USAGE : 0) |
-                            (do_flag_never_null ? ID_REMAP_FLAG_NEVER_NULL_USAGE : 0);
+  const int remap_flags = (do_skip_indirect ? ID_REMAP_SKIP_INDIRECT_USAGE : 0) |
+                          (do_flag_never_null ? ID_REMAP_FLAG_NEVER_NULL_USAGE : 0);
 
   BKE_main_lock(bmain);
 
@@ -756,7 +785,7 @@ void BKE_libblock_relink_multiple(Main *bmain,
                                   LinkNode *ids,
                                   const eIDRemapType remap_type,
                                   struct IDRemapper *id_remapper,
-                                  const short remap_flags)
+                                  const int remap_flags)
 {
   BLI_assert(remap_type == ID_REMAP_TYPE_REMAP || BKE_id_remapper_is_empty(id_remapper));
 
@@ -765,6 +794,10 @@ void BKE_libblock_relink_multiple(Main *bmain,
     libblock_remap_data(bmain, id_iter, remap_type, id_remapper, remap_flags);
   }
 
+  if (bmain == NULL) {
+    return;
+  }
+
   switch (remap_type) {
     case ID_REMAP_TYPE_REMAP: {
       LibBlockRelinkMultipleUserData user_data = {0};
@@ -815,7 +848,7 @@ void BKE_libblock_relink_multiple(Main *bmain,
 }
 
 void BKE_libblock_relink_ex(
-    Main *bmain, void *idv, void *old_idv, void *new_idv, const short remap_flags)
+    Main *bmain, void *idv, void *old_idv, void *new_idv, const int remap_flags)
 {
 
   /* Should be able to replace all _relink() functions (constraints, rigidbody, etc.) ? */
@@ -857,7 +890,8 @@ static void libblock_relink_to_newid_prepare_data(Main *bmain,
 static int id_relink_to_newid_looper(LibraryIDLinkCallbackData *cb_data)
 {
   const int cb_flag = cb_data->cb_flag;
-  if (cb_flag & (IDWALK_CB_EMBEDDED | IDWALK_CB_OVERRIDE_LIBRARY_REFERENCE)) {
+  if (cb_flag & (IDWALK_CB_EMBEDDED | IDWALK_CB_EMBEDDED_NOT_OWNING |
+                 IDWALK_CB_OVERRIDE_LIBRARY_REFERENCE)) {
     return IDWALK_RET_NOP;
   }
 
@@ -904,8 +938,8 @@ void BKE_libblock_relink_to_newid(Main *bmain, ID *id, const int remap_flag)
 
   libblock_relink_to_newid_prepare_data(bmain, id, &relink_data);
 
-  const short remap_flag_final = remap_flag | ID_REMAP_SKIP_INDIRECT_USAGE |
-                                 ID_REMAP_SKIP_OVERRIDE_LIBRARY;
+  const int remap_flag_final = remap_flag | ID_REMAP_SKIP_INDIRECT_USAGE |
+                               ID_REMAP_SKIP_OVERRIDE_LIBRARY;
   BKE_libblock_relink_multiple(
       bmain, relink_data.ids, ID_REMAP_TYPE_REMAP, relink_data.id_remapper, remap_flag_final);
 
diff --git a/source/blender/blenkernel/intern/light.c b/source/blender/blenkernel/intern/light.c
index 42af11294c9..0b777a803bf 100644
--- a/source/blender/blenkernel/intern/light.c
+++ b/source/blender/blenkernel/intern/light.c
@@ -137,8 +137,13 @@ static void light_blend_write(BlendWriter *writer, ID *id, const void *id_addres
 
   /* Node-tree is integral part of lights, no libdata. */
   if (la->nodetree) {
-    BLO_write_struct(writer, bNodeTree, la->nodetree);
-    ntreeBlendWrite(writer, la->nodetree);
+    BLO_Write_IDBuffer *temp_embedded_id_buffer = BLO_write_allocate_id_buffer();
+    BLO_write_init_id_buffer_from_id(
+        temp_embedded_id_buffer, &la->nodetree->id, BLO_write_is_undo(writer));
+    BLO_write_struct_at_address(
+        writer, bNodeTree, la->nodetree, BLO_write_get_id_buffer_temp_id(temp_embedded_id_buffer));
+    ntreeBlendWrite(writer, (bNodeTree *)BLO_write_get_id_buffer_temp_id(temp_embedded_id_buffer));
+    BLO_write_destroy_id_buffer(&temp_embedded_id_buffer);
   }
 
   BKE_previewimg_blend_write(writer, la->preview);
diff --git a/source/blender/blenkernel/intern/linestyle.cc b/source/blender/blenkernel/intern/linestyle.cc
index 8f1c63bb406..de5cd553928 100644
--- a/source/blender/blenkernel/intern/linestyle.cc
+++ b/source/blender/blenkernel/intern/linestyle.cc
@@ -463,8 +463,17 @@ static void linestyle_blend_write(BlendWriter *writer, ID *id, const void *id_ad
     }
   }
   if (linestyle->nodetree) {
-    BLO_write_struct(writer, bNodeTree, linestyle->nodetree);
-    ntreeBlendWrite(writer, linestyle->nodetree);
+    BLO_Write_IDBuffer *temp_embedded_id_buffer = BLO_write_allocate_id_buffer();
+    BLO_write_init_id_buffer_from_id(
+        temp_embedded_id_buffer, &linestyle->nodetree->id, BLO_write_is_undo(writer));
+    BLO_write_struct_at_address(writer,
+                                bNodeTree,
+                                linestyle->nodetree,
+                                BLO_write_get_id_buffer_temp_id(temp_embedded_id_buffer));
+    ntreeBlendWrite(
+        writer,
+        reinterpret_cast<bNodeTree *>(BLO_write_get_id_buffer_temp_id(temp_embedded_id_buffer)));
+    BLO_write_destroy_id_buffer(&temp_embedded_id_buffer);
   }
 }
 
diff --git a/source/blender/blenkernel/intern/material.cc b/source/blender/blenkernel/intern/material.cc
index 1b44c10bf28..fde5a40f765 100644
--- a/source/blender/blenkernel/intern/material.cc
+++ b/source/blender/blenkernel/intern/material.cc
@@ -185,8 +185,15 @@ static void material_blend_write(BlendWriter *writer, ID *id, const void *id_add
 
   /* nodetree is integral part of material, no libdata */
   if (ma->nodetree) {
-    BLO_write_struct(writer, bNodeTree, ma->nodetree);
-    ntreeBlendWrite(writer, ma->nodetree);
+    BLO_Write_IDBuffer *temp_embedded_id_buffer = BLO_write_allocate_id_buffer();
+    BLO_write_init_id_buffer_from_id(
+        temp_embedded_id_buffer, &ma->nodetree->id, BLO_write_is_undo(writer));
+    BLO_write_struct_at_address(
+        writer, bNodeTree, ma->nodetree, BLO_write_get_id_buffer_temp_id(temp_embedded_id_buffer));
+    ntreeBlendWrite(
+        writer,
+        reinterpret_cast<bNodeTree *>(BLO_write_get_id_buffer_temp_id(temp_embedded_id_buffer)));
+    BLO_write_destroy_id_buffer(&temp_embedded_id_buffer);
   }
 
   BKE_previewimg_blend_write(writer, ma->preview);
diff --git a/source/blender/blenkernel/intern/mesh.cc b/source/blender/blenkernel/intern/mesh.cc
index b1ed15eb31b..5f41ce1aa78 100644
--- a/source/blender/blenkernel/intern/mesh.cc
+++ b/source/blender/blenkernel/intern/mesh.cc
@@ -22,6 +22,7 @@
 #include "BLI_endian_switch.h"
 #include "BLI_ghash.h"
 #include "BLI_hash.h"
+#include "BLI_implicit_sharing.hh"
 #include "BLI_index_range.hh"
 #include "BLI_linklist.h"
 #include "BLI_listbase.h"
@@ -154,7 +155,10 @@ static void mesh_copy_data(Main *bmain, ID *id_dst, const ID *id_src, const int
   CustomData_copy(&mesh_src->edata, &mesh_dst->edata, mask.emask, mesh_dst->totedge);
   CustomData_copy(&mesh_src->ldata, &mesh_dst->ldata, mask.lmask, mesh_dst->totloop);
   CustomData_copy(&mesh_src->pdata, &mesh_dst->pdata, mask.pmask, mesh_dst->totpoly);
-  mesh_dst->poly_offset_indices = static_cast<int *>(MEM_dupallocN(mesh_src->poly_offset_indices));
+  blender::implicit_sharing::copy_shared_pointer(mesh_src->poly_offset_indices,
+                                                 mesh_src->runtime->poly_offsets_sharing_info,
+                                                 &mesh_dst->poly_offset_indices,
+                                                 &mesh_dst->runtime->poly_offsets_sharing_info);
   if (do_tessface) {
     CustomData_copy(&mesh_src->fdata, &mesh_dst->fdata, mask.fmask, mesh_dst->totface);
   }
@@ -368,8 +372,6 @@ static void mesh_blend_read_data(BlendDataReader *reader, ID *id)
 
   BLO_read_list(reader, &mesh->vertex_group_names);
 
-  BLO_read_int32_array(reader, mesh->totpoly + 1, &mesh->poly_offset_indices);
-
   CustomData_blend_read(reader, &mesh->vdata, mesh->totvert);
   CustomData_blend_read(reader, &mesh->edata, mesh->totedge);
   CustomData_blend_read(reader, &mesh->fdata, mesh->totface);
@@ -388,6 +390,12 @@ static void mesh_blend_read_data(BlendDataReader *reader, ID *id)
 
   mesh->runtime = new blender::bke::MeshRuntime();
 
+  if (mesh->poly_offset_indices) {
+    BLO_read_int32_array(reader, mesh->totpoly + 1, &mesh->poly_offset_indices);
+    mesh->runtime->poly_offsets_sharing_info = blender::implicit_sharing::info_for_mem_free(
+        mesh->poly_offset_indices);
+  }
+
   /* happens with old files */
   if (mesh->mselect == nullptr) {
     mesh->totselect = 0;
@@ -616,6 +624,16 @@ static int customdata_compare(
           BLI_edgehash_free(eh, nullptr);
           break;
         }
+        case CD_PROP_INT32_2D: {
+          const blender::int2 *l1_data = static_cast<const blender::int2 *>(l1->data);
+          const blender::int2 *l2_data = static_cast<const blender::int2 *>(l2->data);
+          for (int i = 0; i < total_length; i++) {
+            if (l1_data[i] != l2_data[i]) {
+              return MESHCMP_ATTRIBUTE_VALUE_MISMATCH;
+            }
+          }
+          break;
+        }
         case CD_PROP_BYTE_COLOR: {
           MLoopCol *lp1 = (MLoopCol *)l1->data;
           MLoopCol *lp2 = (MLoopCol *)l2->data;
@@ -911,8 +929,10 @@ static void mesh_clear_geometry(Mesh &mesh)
   CustomData_free(&mesh.fdata, mesh.totface);
   CustomData_free(&mesh.ldata, mesh.totloop);
   CustomData_free(&mesh.pdata, mesh.totpoly);
-  MEM_SAFE_FREE(mesh.poly_offset_indices);
-
+  if (mesh.poly_offset_indices) {
+    blender::implicit_sharing::free_shared_data(&mesh.poly_offset_indices,
+                                                &mesh.runtime->poly_offsets_sharing_info);
+  }
   MEM_SAFE_FREE(mesh.mselect);
 
   mesh.totvert = 0;
@@ -966,20 +986,31 @@ Mesh *BKE_mesh_add(Main *bmain, const char *name)
 void BKE_mesh_poly_offsets_ensure_alloc(Mesh *mesh)
 {
   BLI_assert(mesh->poly_offset_indices == nullptr);
+  BLI_assert(mesh->runtime->poly_offsets_sharing_info == nullptr);
   if (mesh->totpoly == 0) {
     return;
   }
   mesh->poly_offset_indices = static_cast<int *>(
       MEM_malloc_arrayN(mesh->totpoly + 1, sizeof(int), __func__));
+  mesh->runtime->poly_offsets_sharing_info = blender::implicit_sharing::info_for_mem_free(
+      mesh->poly_offset_indices);
 
 #ifdef DEBUG
   /* Fill offsets with obviously bad values to simplify finding missing initialization. */
   mesh->poly_offsets_for_write().fill(-1);
 #endif
+  /* Set common values for convenience. */
   mesh->poly_offset_indices[0] = 0;
   mesh->poly_offset_indices[mesh->totpoly] = mesh->totloop;
 }
 
+int *BKE_mesh_poly_offsets_for_write(Mesh *mesh)
+{
+  blender::implicit_sharing::make_trivial_data_mutable(
+      &mesh->poly_offset_indices, &mesh->runtime->poly_offsets_sharing_info, mesh->totpoly + 1);
+  return mesh->poly_offset_indices;
+}
+
 static void mesh_ensure_cdlayers_primary(Mesh &mesh)
 {
   if (!CustomData_get_layer_named(&mesh.vdata, CD_PROP_FLOAT3, "position")) {
diff --git a/source/blender/blenkernel/intern/mesh_convert.cc b/source/blender/blenkernel/intern/mesh_convert.cc
index 343c4a7529f..0e8cbda75ff 100644
--- a/source/blender/blenkernel/intern/mesh_convert.cc
+++ b/source/blender/blenkernel/intern/mesh_convert.cc
@@ -1128,6 +1128,8 @@ void BKE_mesh_nomain_to_mesh(Mesh *mesh_src, Mesh *mesh_dst, Object *ob)
   CustomData_copy(&mesh_src->pdata, &mesh_dst->pdata, mask.pmask, mesh_src->totpoly);
   CustomData_copy(&mesh_src->ldata, &mesh_dst->ldata, mask.lmask, mesh_src->totloop);
   std::swap(mesh_dst->poly_offset_indices, mesh_src->poly_offset_indices);
+  std::swap(mesh_dst->runtime->poly_offsets_sharing_info,
+            mesh_src->runtime->poly_offsets_sharing_info);
 
   /* Make sure attribute names are moved. */
   std::swap(mesh_dst->active_color_attribute, mesh_src->active_color_attribute);
diff --git a/source/blender/blenkernel/intern/mesh_runtime.cc b/source/blender/blenkernel/intern/mesh_runtime.cc
index 7935b6d692b..714d5edacb1 100644
--- a/source/blender/blenkernel/intern/mesh_runtime.cc
+++ b/source/blender/blenkernel/intern/mesh_runtime.cc
@@ -241,6 +241,7 @@ void BKE_mesh_tag_edges_split(struct Mesh *mesh)
   mesh->runtime->subsurf_optimal_display_edges.clear_and_shrink();
   if (mesh->runtime->shrinkwrap_data) {
     BKE_shrinkwrap_boundary_data_free(mesh->runtime->shrinkwrap_data);
+    mesh->runtime->shrinkwrap_data = nullptr;
   }
 }
 
diff --git a/source/blender/blenkernel/intern/scene.cc b/source/blender/blenkernel/intern/scene.cc
index b0d16a98b00..0550c2ed338 100644
--- a/source/blender/blenkernel/intern/scene.cc
+++ b/source/blender/blenkernel/intern/scene.cc
@@ -763,7 +763,7 @@ static void scene_foreach_layer_collection(LibraryForeachIDData *data, ListBase
      * anyway... */
     const int cb_flag = (lc->collection != nullptr &&
                          (lc->collection->id.flag & LIB_EMBEDDED_DATA) != 0) ?
-                            IDWALK_CB_EMBEDDED :
+                            IDWALK_CB_EMBEDDED_NOT_OWNING :
                             IDWALK_CB_NOP;
     BKE_LIB_FOREACHID_PROCESS_IDSUPER(data, lc->collection, cb_flag | IDWALK_CB_DIRECT_WEAK_LINK);
     scene_foreach_layer_collection(data, &lc->layer_collections);
@@ -947,6 +947,8 @@ static void scene_blend_write(BlendWriter *writer, ID *id, const void *id_addres
 {
   Scene *sce = (Scene *)id;
 
+  BLO_Write_IDBuffer *temp_embedded_id_buffer = BLO_write_allocate_id_buffer();
+
   if (BLO_write_is_undo(writer)) {
     /* Clean up, important in undo case to reduce false detection of changed data-blocks. */
     /* XXX This UI data should not be stored in Scene at all... */
@@ -1074,8 +1076,15 @@ static void scene_blend_write(BlendWriter *writer, ID *id, const void *id_addres
   }
 
   if (sce->nodetree) {
-    BLO_write_struct(writer, bNodeTree, sce->nodetree);
-    ntreeBlendWrite(writer, sce->nodetree);
+    BLO_write_init_id_buffer_from_id(
+        temp_embedded_id_buffer, &sce->nodetree->id, BLO_write_is_undo(writer));
+    BLO_write_struct_at_address(writer,
+                                bNodeTree,
+                                sce->nodetree,
+                                BLO_write_get_id_buffer_temp_id(temp_embedded_id_buffer));
+    ntreeBlendWrite(
+        writer,
+        reinterpret_cast<bNodeTree *>(BLO_write_get_id_buffer_temp_id(temp_embedded_id_buffer)));
   }
 
   BKE_color_managed_view_settings_blend_write(writer, &sce->view_settings);
@@ -1102,8 +1111,15 @@ static void scene_blend_write(BlendWriter *writer, ID *id, const void *id_addres
   }
 
   if (sce->master_collection) {
-    BLO_write_struct(writer, Collection, sce->master_collection);
-    BKE_collection_blend_write_nolib(writer, sce->master_collection);
+    BLO_write_init_id_buffer_from_id(
+        temp_embedded_id_buffer, &sce->master_collection->id, BLO_write_is_undo(writer));
+    BLO_write_struct_at_address(writer,
+                                Collection,
+                                sce->master_collection,
+                                BLO_write_get_id_buffer_temp_id(temp_embedded_id_buffer));
+    BKE_collection_blend_write_nolib(
+        writer,
+        reinterpret_cast<Collection *>(BLO_write_get_id_buffer_temp_id(temp_embedded_id_buffer)));
   }
 
   /* Eevee Light-cache */
@@ -1116,6 +1132,8 @@ static void scene_blend_write(BlendWriter *writer, ID *id, const void *id_addres
 
   /* Freed on `do_versions()`. */
   BLI_assert(sce->layer_properties == nullptr);
+
+  BLO_write_destroy_id_buffer(&temp_embedded_id_buffer);
 }
 
 static void direct_link_paint_helper(BlendDataReader *reader, const Scene *scene, Paint **paint)
diff --git a/source/blender/blenkernel/intern/screen.c b/source/blender/blenkernel/intern/screen.c
index c62443303f1..7c60d2351fc 100644
--- a/source/blender/blenkernel/intern/screen.c
+++ b/source/blender/blenkernel/intern/screen.c
@@ -85,6 +85,9 @@ static void screen_foreach_id_dopesheet(LibraryForeachIDData *data, bDopeSheet *
 
 void BKE_screen_foreach_id_screen_area(LibraryForeachIDData *data, ScrArea *area)
 {
+  const bool is_readonly = (BKE_lib_query_foreachid_process_flags_get(data) & IDWALK_READONLY) !=
+                           0;
+
   BKE_LIB_FOREACHID_PROCESS_IDSUPER(data, area->full, IDWALK_CB_NOP);
 
   /* TODO: this should be moved to a callback in `SpaceType`, defined in each editor's own code.
@@ -105,26 +108,55 @@ void BKE_screen_foreach_id_screen_area(LibraryForeachIDData *data, ScrArea *area
         SpaceGraph *sipo = (SpaceGraph *)sl;
         BKE_LIB_FOREACHID_PROCESS_FUNCTION_CALL(data,
                                                 screen_foreach_id_dopesheet(data, sipo->ads));
+
+        if (!is_readonly) {
+          /* Force recalc of list of channels (i.e. including calculating F-Curve colors) to
+           * prevent the "black curves" problem post-undo. */
+          sipo->runtime.flag |= SIPO_RUNTIME_FLAG_NEED_CHAN_SYNC_COLOR;
+        }
         break;
       }
       case SPACE_PROPERTIES: {
         SpaceProperties *sbuts = (SpaceProperties *)sl;
         BKE_LIB_FOREACHID_PROCESS_ID(data, sbuts->pinid, IDWALK_CB_NOP);
+        if (!is_readonly) {
+          if (sbuts->pinid == NULL) {
+            sbuts->flag &= ~SB_PIN_CONTEXT;
+          }
+          /* Note: Restoring path pointers is complicated, if not impossible, because this contains
+           * data pointers too, not just ID ones. See #40046. */
+          MEM_SAFE_FREE(sbuts->path);
+        }
         break;
       }
-      case SPACE_FILE:
+      case SPACE_FILE: {
+        if (!is_readonly) {
+          SpaceFile *sfile = (SpaceFile *)sl;
+          sfile->op = NULL;
+          sfile->tags = FILE_TAG_REBUILD_MAIN_FILES;
+        }
         break;
+      }
       case SPACE_ACTION: {
         SpaceAction *saction = (SpaceAction *)sl;
         screen_foreach_id_dopesheet(data, &saction->ads);
         BKE_LIB_FOREACHID_PROCESS_IDSUPER(data, saction->action, IDWALK_CB_NOP);
+        if (!is_readonly) {
+          /* Force recalc of list of channels, potentially updating the active action while we're
+           * at it (as it can only be updated that way) #28962. */
+          saction->runtime.flag |= SACTION_RUNTIME_FLAG_NEED_CHAN_SYNC;
+        }
         break;
       }
       case SPACE_IMAGE: {
         SpaceImage *sima = (SpaceImage *)sl;
         BKE_LIB_FOREACHID_PROCESS_IDSUPER(data, sima->image, IDWALK_CB_USER_ONE);
+        BKE_LIB_FOREACHID_PROCESS_IDSUPER(data, sima->iuser.scene, IDWALK_CB_NOP);
         BKE_LIB_FOREACHID_PROCESS_IDSUPER(data, sima->mask_info.mask, IDWALK_CB_USER_ONE);
         BKE_LIB_FOREACHID_PROCESS_IDSUPER(data, sima->gpd, IDWALK_CB_USER);
+        if (!is_readonly) {
+          sima->scopes.ok = 0;
+        }
         break;
       }
       case SPACE_SEQ: {
@@ -156,45 +188,106 @@ void BKE_screen_foreach_id_screen_area(LibraryForeachIDData *data, ScrArea *area
 
           BLI_mempool_iternew(space_outliner->treestore, &iter);
           while ((tselem = BLI_mempool_iterstep(&iter))) {
-            BKE_LIB_FOREACHID_PROCESS_ID(data, tselem->id, IDWALK_CB_NOP);
+            /* Do not try to restore non-ID pointers (drivers/sequence/etc.). */
+            if (TSE_IS_REAL_ID(tselem)) {
+              const int cb_flag = (tselem->id != NULL &&
+                                   (tselem->id->flag & LIB_EMBEDDED_DATA) != 0) ?
+                                      IDWALK_CB_EMBEDDED_NOT_OWNING :
+                                      IDWALK_CB_NOP;
+              BKE_LIB_FOREACHID_PROCESS_ID(data, tselem->id, cb_flag);
+            }
+            else if (!is_readonly) {
+              tselem->id = NULL;
+            }
+          }
+          if (!is_readonly) {
+            /* rebuild hash table, because it depends on ids too */
+            space_outliner->storeflag |= SO_TREESTORE_REBUILD;
           }
         }
         break;
       }
       case SPACE_NODE: {
         SpaceNode *snode = (SpaceNode *)sl;
-        const bool is_private_nodetree = snode->id != NULL &&
-                                         ntreeFromID(snode->id) == snode->nodetree;
+        const bool is_embedded_nodetree = snode->id != NULL &&
+                                          ntreeFromID(snode->id) == snode->nodetree;
 
         BKE_LIB_FOREACHID_PROCESS_ID(data, snode->id, IDWALK_CB_NOP);
         BKE_LIB_FOREACHID_PROCESS_ID(data, snode->from, IDWALK_CB_NOP);
-        BKE_LIB_FOREACHID_PROCESS_IDSUPER(
-            data, snode->nodetree, is_private_nodetree ? IDWALK_CB_EMBEDDED : IDWALK_CB_USER_ONE);
 
-        LISTBASE_FOREACH (bNodeTreePath *, path, &snode->treepath) {
-          if (path == snode->treepath.first) {
-            /* first nodetree in path is same as snode->nodetree */
-            BKE_LIB_FOREACHID_PROCESS_IDSUPER(data,
-                                              path->nodetree,
-                                              is_private_nodetree ? IDWALK_CB_EMBEDDED :
-                                                                    IDWALK_CB_USER_ONE);
+        bNodeTreePath *path = snode->treepath.first;
+        BLI_assert(path == NULL || path->nodetree == snode->nodetree);
+
+        if (is_embedded_nodetree) {
+          BKE_LIB_FOREACHID_PROCESS_IDSUPER(data, snode->nodetree, IDWALK_CB_EMBEDDED_NOT_OWNING);
+          if (path != NULL) {
+            BKE_LIB_FOREACHID_PROCESS_IDSUPER(data, path->nodetree, IDWALK_CB_EMBEDDED_NOT_OWNING);
           }
-          else {
+
+          /* Embedded ID pointers are not remapped (besides exceptions), ensure it still matches
+           * actual data. Note that `snode->id` was already processed (and therefore potentially
+           * remapped) above.*/
+          if (!is_readonly && path != NULL) {
+            path->nodetree = snode->nodetree = (snode->id == NULL) ? NULL : ntreeFromID(snode->id);
+          }
+        }
+        else {
+          BKE_LIB_FOREACHID_PROCESS_IDSUPER(data, snode->nodetree, IDWALK_CB_USER_ONE);
+          if (path != NULL) {
             BKE_LIB_FOREACHID_PROCESS_IDSUPER(data, path->nodetree, IDWALK_CB_USER_ONE);
           }
-
-          if (path->nodetree == NULL) {
-            break;
-          }
         }
 
-        BKE_LIB_FOREACHID_PROCESS_IDSUPER(data, snode->edittree, IDWALK_CB_NOP);
+        if (path != NULL) {
+          for (path = path->next; path != NULL; path = path->next) {
+            BLI_assert(path->nodetree != NULL);
+            BLI_assert((path->nodetree->id.flag & LIB_EMBEDDED_DATA) == 0);
+
+            BKE_LIB_FOREACHID_PROCESS_IDSUPER(data, path->nodetree, IDWALK_CB_USER_ONE);
+
+            if (path->nodetree == NULL) {
+              BLI_assert(!is_readonly);
+              /* Remaining path entries are invalid, remove them. */
+              for (bNodeTreePath *path_next; path; path = path_next) {
+                path_next = path->next;
+                BLI_remlink(&snode->treepath, path);
+                MEM_freeN(path);
+              }
+              break;
+            }
+          }
+        }
+        BLI_assert(path == NULL);
+
+        if (!is_readonly) {
+          /* `edittree` is just the last in the path, set this directly since the path may have
+           * been shortened above. */
+          if (snode->treepath.last != NULL) {
+            path = snode->treepath.last;
+            snode->edittree = path->nodetree;
+          }
+          else {
+            snode->edittree = NULL;
+          }
+        }
+        /* NOTE: It is disputable whether this should be called here, especially when editing it is
+         * allowed? But for now, for sake of consistency, do it in any case. */
+        if (is_embedded_nodetree && snode->edittree == snode->nodetree) {
+          BKE_LIB_FOREACHID_PROCESS_IDSUPER(data, snode->edittree, IDWALK_CB_EMBEDDED_NOT_OWNING);
+        }
+        else {
+          BKE_LIB_FOREACHID_PROCESS_IDSUPER(data, snode->edittree, IDWALK_CB_NOP);
+        }
         break;
       }
       case SPACE_CLIP: {
         SpaceClip *sclip = (SpaceClip *)sl;
         BKE_LIB_FOREACHID_PROCESS_IDSUPER(data, sclip->clip, IDWALK_CB_USER_ONE);
         BKE_LIB_FOREACHID_PROCESS_IDSUPER(data, sclip->mask_info.mask, IDWALK_CB_USER_ONE);
+
+        if (!is_readonly) {
+          sclip->scopes.ok = 0;
+        }
         break;
       }
       case SPACE_SPREADSHEET: {
diff --git a/source/blender/blenkernel/intern/simulation.cc b/source/blender/blenkernel/intern/simulation.cc
index c0e67b910f0..dabdad4b79f 100644
--- a/source/blender/blenkernel/intern/simulation.cc
+++ b/source/blender/blenkernel/intern/simulation.cc
@@ -107,8 +107,17 @@ static void simulation_blend_write(BlendWriter *writer, ID *id, const void *id_a
 
   /* nodetree is integral part of simulation, no libdata */
   if (simulation->nodetree) {
-    BLO_write_struct(writer, bNodeTree, simulation->nodetree);
-    ntreeBlendWrite(writer, simulation->nodetree);
+    BLO_Write_IDBuffer *temp_embedded_id_buffer = BLO_write_allocate_id_buffer();
+    BLO_write_init_id_buffer_from_id(
+        temp_embedded_id_buffer, &simulation->nodetree->id, BLO_write_is_undo(writer));
+    BLO_write_struct_at_address(writer,
+                                bNodeTree,
+                                simulation->nodetree,
+                                BLO_write_get_id_buffer_temp_id(temp_embedded_id_buffer));
+    ntreeBlendWrite(
+        writer,
+        reinterpret_cast<bNodeTree *>(BLO_write_get_id_buffer_temp_id(temp_embedded_id_buffer)));
+    BLO_write_destroy_id_buffer(&temp_embedded_id_buffer);
   }
 }
 
diff --git a/source/blender/blenkernel/intern/texture.cc b/source/blender/blenkernel/intern/texture.cc
index ed385fae454..d2cb4c4b201 100644
--- a/source/blender/blenkernel/intern/texture.cc
+++ b/source/blender/blenkernel/intern/texture.cc
@@ -155,8 +155,17 @@ static void texture_blend_write(BlendWriter *writer, ID *id, const void *id_addr
 
   /* nodetree is integral part of texture, no libdata */
   if (tex->nodetree) {
-    BLO_write_struct(writer, bNodeTree, tex->nodetree);
-    ntreeBlendWrite(writer, tex->nodetree);
+    BLO_Write_IDBuffer *temp_embedded_id_buffer = BLO_write_allocate_id_buffer();
+    BLO_write_init_id_buffer_from_id(
+        temp_embedded_id_buffer, &tex->nodetree->id, BLO_write_is_undo(writer));
+    BLO_write_struct_at_address(writer,
+                                bNodeTree,
+                                tex->nodetree,
+                                BLO_write_get_id_buffer_temp_id(temp_embedded_id_buffer));
+    ntreeBlendWrite(
+        writer,
+        reinterpret_cast<bNodeTree *>(BLO_write_get_id_buffer_temp_id(temp_embedded_id_buffer)));
+    BLO_write_destroy_id_buffer(&temp_embedded_id_buffer);
   }
 
   BKE_previewimg_blend_write(writer, tex->preview);
diff --git a/source/blender/blenkernel/intern/type_conversions.cc b/source/blender/blenkernel/intern/type_conversions.cc
index f1dea155225..094fb628698 100644
--- a/source/blender/blenkernel/intern/type_conversions.cc
+++ b/source/blender/blenkernel/intern/type_conversions.cc
@@ -51,6 +51,10 @@ static int32_t float_to_int(const float &a)
 {
   return int32_t(a);
 }
+static int2 float_to_int2(const float &a)
+{
+  return int2(a);
+}
 static bool float_to_bool(const float &a)
 {
   return a > 0.0f;
@@ -81,6 +85,10 @@ static int float2_to_int(const float2 &a)
 {
   return int32_t((a.x + a.y) / 2.0f);
 }
+static int2 float2_to_int2(const float2 &a)
+{
+  return int2(a.x, a.y);
+}
 static bool float2_to_bool(const float2 &a)
 {
   return !math::is_zero(a);
@@ -114,6 +122,10 @@ static int float3_to_int(const float3 &a)
 {
   return int((a.x + a.y + a.z) / 3.0f);
 }
+static int2 float3_to_int2(const float3 &a)
+{
+  return int2(a.x, a.y);
+}
 static float2 float3_to_float2(const float3 &a)
 {
   return float2(a);
@@ -136,6 +148,10 @@ static int8_t int_to_int8(const int32_t &a)
   return std::clamp(
       a, int(std::numeric_limits<int8_t>::min()), int(std::numeric_limits<int8_t>::max()));
 }
+static int2 int_to_int2(const int32_t &a)
+{
+  return int2(a);
+}
 static float int_to_float(const int32_t &a)
 {
   return float(a);
@@ -157,6 +173,39 @@ static ColorGeometry4b int_to_byte_color(const int32_t &a)
   return int_to_color(a).encode();
 }
 
+static bool int2_to_bool(const int2 &a)
+{
+  return !math::is_zero(a);
+}
+static float2 int2_to_float2(const int2 &a)
+{
+  return float2(a);
+}
+static int int2_to_int(const int2 &a)
+{
+  return math::midpoint(a.x, a.y);
+}
+static int8_t int2_to_int8(const int2 &a)
+{
+  return int_to_int8(int2_to_int(a));
+}
+static float int2_to_float(const int2 &a)
+{
+  return float2_to_float(float2(a));
+}
+static float3 int2_to_float3(const int2 &a)
+{
+  return float3(float(a.x), float(a.y), 0.0f);
+}
+static ColorGeometry4f int2_to_color(const int2 &a)
+{
+  return ColorGeometry4f(float(a.x), float(a.y), 0.0f, 1.0f);
+}
+static ColorGeometry4b int2_to_byte_color(const int2 &a)
+{
+  return int2_to_color(a).encode();
+}
+
 static bool int8_to_bool(const int8_t &a)
 {
   return a > 0;
@@ -165,6 +214,10 @@ static int int8_to_int(const int8_t &a)
 {
   return int(a);
 }
+static int2 int8_to_int2(const int8_t &a)
+{
+  return int2(a);
+}
 static float int8_to_float(const int8_t &a)
 {
   return float(a);
@@ -198,6 +251,10 @@ static int32_t bool_to_int(const bool &a)
 {
   return int32_t(a);
 }
+static int2 bool_to_int2(const bool &a)
+{
+  return int2(a);
+}
 static float2 bool_to_float2(const bool &a)
 {
   return (a) ? float2(1.0f) : float2(0.0f);
@@ -227,6 +284,10 @@ static int32_t color_to_int(const ColorGeometry4f &a)
 {
   return int(rgb_to_grayscale(a));
 }
+static int2 color_to_int2(const ColorGeometry4f &a)
+{
+  return int2(a.r, a.g);
+}
 static int8_t color_to_int8(const ColorGeometry4f &a)
 {
   return int_to_int8(color_to_int(a));
@@ -256,6 +317,10 @@ static int32_t byte_color_to_int(const ColorGeometry4b &a)
 {
   return color_to_int(a.decode());
 }
+static int2 byte_color_to_int2(const ColorGeometry4b &a)
+{
+  return int2(a.r, a.g);
+}
 static int8_t byte_color_to_int8(const ColorGeometry4b &a)
 {
   return color_to_int8(a.decode());
@@ -280,6 +345,7 @@ static DataTypeConversions create_implicit_conversions()
   add_implicit_conversion<float, float2, float_to_float2>(conversions);
   add_implicit_conversion<float, float3, float_to_float3>(conversions);
   add_implicit_conversion<float, int32_t, float_to_int>(conversions);
+  add_implicit_conversion<float, int2, float_to_int2>(conversions);
   add_implicit_conversion<float, bool, float_to_bool>(conversions);
   add_implicit_conversion<float, int8_t, float_to_int8>(conversions);
   add_implicit_conversion<float, ColorGeometry4f, float_to_color>(conversions);
@@ -288,6 +354,7 @@ static DataTypeConversions create_implicit_conversions()
   add_implicit_conversion<float2, float3, float2_to_float3>(conversions);
   add_implicit_conversion<float2, float, float2_to_float>(conversions);
   add_implicit_conversion<float2, int32_t, float2_to_int>(conversions);
+  add_implicit_conversion<float2, int2, float2_to_int2>(conversions);
   add_implicit_conversion<float2, bool, float2_to_bool>(conversions);
   add_implicit_conversion<float2, int8_t, float2_to_int8>(conversions);
   add_implicit_conversion<float2, ColorGeometry4f, float2_to_color>(conversions);
@@ -297,20 +364,32 @@ static DataTypeConversions create_implicit_conversions()
   add_implicit_conversion<float3, int8_t, float3_to_int8>(conversions);
   add_implicit_conversion<float3, float, float3_to_float>(conversions);
   add_implicit_conversion<float3, int32_t, float3_to_int>(conversions);
+  add_implicit_conversion<float3, int2, float3_to_int2>(conversions);
   add_implicit_conversion<float3, float2, float3_to_float2>(conversions);
   add_implicit_conversion<float3, ColorGeometry4f, float3_to_color>(conversions);
   add_implicit_conversion<float3, ColorGeometry4b, float3_to_byte_color>(conversions);
 
   add_implicit_conversion<int32_t, bool, int_to_bool>(conversions);
   add_implicit_conversion<int32_t, int8_t, int_to_int8>(conversions);
+  add_implicit_conversion<int32_t, int2, int_to_int2>(conversions);
   add_implicit_conversion<int32_t, float, int_to_float>(conversions);
   add_implicit_conversion<int32_t, float2, int_to_float2>(conversions);
   add_implicit_conversion<int32_t, float3, int_to_float3>(conversions);
   add_implicit_conversion<int32_t, ColorGeometry4f, int_to_color>(conversions);
   add_implicit_conversion<int32_t, ColorGeometry4b, int_to_byte_color>(conversions);
 
+  add_implicit_conversion<int2, bool, int2_to_bool>(conversions);
+  add_implicit_conversion<int2, int8_t, int2_to_int8>(conversions);
+  add_implicit_conversion<int2, int, int2_to_int>(conversions);
+  add_implicit_conversion<int2, float, int2_to_float>(conversions);
+  add_implicit_conversion<int2, float2, int2_to_float2>(conversions);
+  add_implicit_conversion<int2, float3, int2_to_float3>(conversions);
+  add_implicit_conversion<int2, ColorGeometry4f, int2_to_color>(conversions);
+  add_implicit_conversion<int2, ColorGeometry4b, int2_to_byte_color>(conversions);
+
   add_implicit_conversion<int8_t, bool, int8_to_bool>(conversions);
   add_implicit_conversion<int8_t, int32_t, int8_to_int>(conversions);
+  add_implicit_conversion<int8_t, int2, int8_to_int2>(conversions);
   add_implicit_conversion<int8_t, float, int8_to_float>(conversions);
   add_implicit_conversion<int8_t, float2, int8_to_float2>(conversions);
   add_implicit_conversion<int8_t, float3, int8_to_float3>(conversions);
@@ -320,6 +399,7 @@ static DataTypeConversions create_implicit_conversions()
   add_implicit_conversion<bool, float, bool_to_float>(conversions);
   add_implicit_conversion<bool, int8_t, bool_to_int8>(conversions);
   add_implicit_conversion<bool, int32_t, bool_to_int>(conversions);
+  add_implicit_conversion<bool, int2, bool_to_int2>(conversions);
   add_implicit_conversion<bool, float2, bool_to_float2>(conversions);
   add_implicit_conversion<bool, float3, bool_to_float3>(conversions);
   add_implicit_conversion<bool, ColorGeometry4f, bool_to_color>(conversions);
@@ -329,6 +409,7 @@ static DataTypeConversions create_implicit_conversions()
   add_implicit_conversion<ColorGeometry4f, int8_t, color_to_int8>(conversions);
   add_implicit_conversion<ColorGeometry4f, float, color_to_float>(conversions);
   add_implicit_conversion<ColorGeometry4f, int32_t, color_to_int>(conversions);
+  add_implicit_conversion<ColorGeometry4f, int2, color_to_int2>(conversions);
   add_implicit_conversion<ColorGeometry4f, float2, color_to_float2>(conversions);
   add_implicit_conversion<ColorGeometry4f, float3, color_to_float3>(conversions);
   add_implicit_conversion<ColorGeometry4f, ColorGeometry4b, color_to_byte_color>(conversions);
@@ -337,6 +418,7 @@ static DataTypeConversions create_implicit_conversions()
   add_implicit_conversion<ColorGeometry4b, int8_t, byte_color_to_int8>(conversions);
   add_implicit_conversion<ColorGeometry4b, float, byte_color_to_float>(conversions);
   add_implicit_conversion<ColorGeometry4b, int32_t, byte_color_to_int>(conversions);
+  add_implicit_conversion<ColorGeometry4b, int2, byte_color_to_int2>(conversions);
   add_implicit_conversion<ColorGeometry4b, float2, byte_color_to_float2>(conversions);
   add_implicit_conversion<ColorGeometry4b, float3, byte_color_to_float3>(conversions);
   add_implicit_conversion<ColorGeometry4b, ColorGeometry4f, byte_color_to_color>(conversions);
diff --git a/source/blender/blenkernel/intern/world.c b/source/blender/blenkernel/intern/world.c
index c6c50ee068c..988e3e7a02e 100644
--- a/source/blender/blenkernel/intern/world.c
+++ b/source/blender/blenkernel/intern/world.c
@@ -144,8 +144,15 @@ static void world_blend_write(BlendWriter *writer, ID *id, const void *id_addres
 
   /* nodetree is integral part of world, no libdata */
   if (wrld->nodetree) {
-    BLO_write_struct(writer, bNodeTree, wrld->nodetree);
-    ntreeBlendWrite(writer, wrld->nodetree);
+    BLO_Write_IDBuffer *temp_embedded_id_buffer = BLO_write_allocate_id_buffer();
+    BLO_write_init_id_buffer_from_id(
+        temp_embedded_id_buffer, &wrld->nodetree->id, BLO_write_is_undo(writer));
+    BLO_write_struct_at_address(writer,
+                                bNodeTree,
+                                wrld->nodetree,
+                                BLO_write_get_id_buffer_temp_id(temp_embedded_id_buffer));
+    ntreeBlendWrite(writer, (bNodeTree *)BLO_write_get_id_buffer_temp_id(temp_embedded_id_buffer));
+    BLO_write_destroy_id_buffer(&temp_embedded_id_buffer);
   }
 
   BKE_previewimg_blend_write(writer, wrld->preview);
diff --git a/source/blender/blenlib/BLI_implicit_sharing.hh b/source/blender/blenlib/BLI_implicit_sharing.hh
index cb74367203c..36feadd4f1e 100644
--- a/source/blender/blenlib/BLI_implicit_sharing.hh
+++ b/source/blender/blenlib/BLI_implicit_sharing.hh
@@ -102,4 +102,83 @@ class ImplicitSharingMixin : public ImplicitSharingInfo {
   virtual void delete_self() = 0;
 };
 
+namespace implicit_sharing {
+
+namespace detail {
+
+void *resize_trivial_array_impl(void *old_data,
+                                int64_t old_size,
+                                int64_t new_size,
+                                int64_t alignment,
+                                ImplicitSharingInfo **sharing_info);
+void *make_trivial_data_mutable_impl(void *old_data,
+                                     int64_t size,
+                                     int64_t alignment,
+                                     ImplicitSharingInfo **sharing_info);
+
+}  // namespace detail
+
+/**
+ * Copy shared data from the source to the destination, adding a user count.
+ * \note Does not free any existing data in the destination.
+ */
+template<typename T>
+void copy_shared_pointer(T *src_ptr,
+                         ImplicitSharingInfo *src_sharing_info,
+                         T **r_dst_ptr,
+                         ImplicitSharingInfo **r_dst_sharing_info)
+{
+  *r_dst_ptr = src_ptr;
+  *r_dst_sharing_info = src_sharing_info;
+  if (*r_dst_ptr) {
+    BLI_assert(*r_dst_sharing_info != nullptr);
+    (*r_dst_sharing_info)->add_user();
+  }
+}
+
+/**
+ * Remove this reference to the shared data and remove dangling pointers.
+ */
+template<typename T> void free_shared_data(T **data, ImplicitSharingInfo **sharing_info)
+{
+  if (*sharing_info) {
+    BLI_assert(*data != nullptr);
+    (*sharing_info)->remove_user_and_delete_if_last();
+  }
+  *data = nullptr;
+  *sharing_info = nullptr;
+}
+
+/**
+ * Create an implicit sharing object that takes ownership of the data, allowing it to be shared.
+ * When it is no longer used, the data is freed with #MEM_freeN, so it must be a trivial type.
+ */
+ImplicitSharingInfo *info_for_mem_free(void *data);
+
+/**
+ * Make data mutable (single-user) if it is shared. For trivially-copyable data only.
+ */
+template<typename T>
+void make_trivial_data_mutable(T **data, ImplicitSharingInfo **sharing_info, const int64_t size)
+{
+  *data = static_cast<T *>(
+      detail::make_trivial_data_mutable_impl(*data, sizeof(T) * size, alignof(T), sharing_info));
+}
+
+/**
+ * Resize an array of shared data. For trivially-copyable data only. Any new values are not
+ * initialized.
+ */
+template<typename T>
+void resize_trivial_array(T **data,
+                          ImplicitSharingInfo **sharing_info,
+                          int64_t old_size,
+                          int64_t new_size)
+{
+  *data = static_cast<T *>(detail::resize_trivial_array_impl(
+      *data, sizeof(T) * old_size, sizeof(T) * new_size, alignof(T), sharing_info));
+}
+
+}  // namespace implicit_sharing
+
 }  // namespace blender
diff --git a/source/blender/blenlib/BLI_math_base.hh b/source/blender/blenlib/BLI_math_base.hh
index 87280eead3a..9ea04d604e4 100644
--- a/source/blender/blenlib/BLI_math_base.hh
+++ b/source/blender/blenlib/BLI_math_base.hh
@@ -194,11 +194,22 @@ inline T interpolate(const T &a, const T &b, const FactorT &t)
 
 template<typename T> inline T midpoint(const T &a, const T &b)
 {
-  auto result = (a + b) * T(0.5);
   if constexpr (std::is_integral_v<T>) {
-    result = std::round(result);
+    /** See std::midpoint from C++20. */
+    using Unsigned = std::make_unsigned_t<T>;
+    int sign = 1;
+    Unsigned smaller = a;
+    Unsigned larger = b;
+    if (a > b) {
+      sign = -1;
+      smaller = b;
+      larger = a;
+    }
+    return a + sign * T(Unsigned(larger - smaller) / 2);
+  }
+  else {
+    return (a + b) * T(0.5);
   }
-  return result;
 }
 
 }  // namespace blender::math
diff --git a/source/blender/blenlib/CMakeLists.txt b/source/blender/blenlib/CMakeLists.txt
index 9d80bce832e..8fd83c849a1 100644
--- a/source/blender/blenlib/CMakeLists.txt
+++ b/source/blender/blenlib/CMakeLists.txt
@@ -83,6 +83,7 @@ set(SRC
   intern/hash_md5.c
   intern/hash_mm2a.c
   intern/hash_mm3.c
+  intern/implicit_sharing.cc
   intern/index_mask.cc
   intern/jitter_2d.c
   intern/kdtree_1d.c
diff --git a/source/blender/blenlib/PIL_time_utildefines.h b/source/blender/blenlib/PIL_time_utildefines.h
index 03d69647b28..a9cf3351e32 100644
--- a/source/blender/blenlib/PIL_time_utildefines.h
+++ b/source/blender/blenlib/PIL_time_utildefines.h
@@ -104,6 +104,8 @@
   } \
   (void)0
 
+#define TIMEIT_BLOCK_VALUE(id) (float)(_timeit_var_##id)
+
 #define TIMEIT_BLOCK_STATS(id) \
   { \
     printf("%s time (in seconds): %f\n", #id, _timeit_var_##id); \
diff --git a/source/blender/blenlib/intern/cpp_types.cc b/source/blender/blenlib/intern/cpp_types.cc
index 083869c409d..573feff49b0 100644
--- a/source/blender/blenlib/intern/cpp_types.cc
+++ b/source/blender/blenlib/intern/cpp_types.cc
@@ -52,6 +52,7 @@ BLI_CPP_TYPE_MAKE(blender::float4x4, CPPTypeFlags::BasicType)
 BLI_CPP_TYPE_MAKE(int8_t, CPPTypeFlags::BasicType)
 BLI_CPP_TYPE_MAKE(int16_t, CPPTypeFlags::BasicType)
 BLI_CPP_TYPE_MAKE(int32_t, CPPTypeFlags::BasicType)
+BLI_CPP_TYPE_MAKE(blender::int2, CPPTypeFlags::BasicType)
 BLI_CPP_TYPE_MAKE(int64_t, CPPTypeFlags::BasicType)
 
 BLI_CPP_TYPE_MAKE(uint8_t, CPPTypeFlags::BasicType)
@@ -80,6 +81,7 @@ void register_cpp_types()
   BLI_CPP_TYPE_REGISTER(int8_t);
   BLI_CPP_TYPE_REGISTER(int16_t);
   BLI_CPP_TYPE_REGISTER(int32_t);
+  BLI_CPP_TYPE_REGISTER(blender::int2);
   BLI_CPP_TYPE_REGISTER(int64_t);
 
   BLI_CPP_TYPE_REGISTER(uint8_t);
diff --git a/source/blender/blenlib/intern/implicit_sharing.cc b/source/blender/blenlib/intern/implicit_sharing.cc
new file mode 100644
index 00000000000..3ab1b61c1a5
--- /dev/null
+++ b/source/blender/blenlib/intern/implicit_sharing.cc
@@ -0,0 +1,100 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <algorithm>
+#include <cstring>
+
+#include "MEM_guardedalloc.h"
+
+#include "BLI_implicit_sharing.hh"
+
+namespace blender::implicit_sharing {
+
+class MEMFreeImplicitSharing : public ImplicitSharingInfo {
+ public:
+  void *data;
+
+  MEMFreeImplicitSharing(void *data) : ImplicitSharingInfo(1), data(data)
+  {
+    BLI_assert(data != nullptr);
+  }
+
+ private:
+  void delete_self_with_data() override
+  {
+    MEM_freeN(data);
+    MEM_delete(this);
+  }
+};
+
+ImplicitSharingInfo *info_for_mem_free(void *data)
+{
+  return MEM_new<MEMFreeImplicitSharing>(__func__, data);
+}
+
+namespace detail {
+
+void *make_trivial_data_mutable_impl(void *old_data,
+                                     const int64_t size,
+                                     const int64_t alignment,
+                                     ImplicitSharingInfo **sharing_info)
+{
+  if (!old_data) {
+    BLI_assert(size == 0);
+    return nullptr;
+  }
+
+  BLI_assert(*sharing_info != nullptr);
+  if ((*sharing_info)->is_shared()) {
+    void *new_data = MEM_mallocN_aligned(size, alignment, __func__);
+    memcpy(new_data, old_data, size);
+    (*sharing_info)->remove_user_and_delete_if_last();
+    *sharing_info = info_for_mem_free(new_data);
+    return new_data;
+  }
+
+  return old_data;
+}
+
+void *resize_trivial_array_impl(void *old_data,
+                                const int64_t old_size,
+                                const int64_t new_size,
+                                const int64_t alignment,
+                                ImplicitSharingInfo **sharing_info)
+{
+  if (new_size == 0) {
+    if (*sharing_info) {
+      (*sharing_info)->remove_user_and_delete_if_last();
+      *sharing_info = nullptr;
+    }
+    return nullptr;
+  }
+
+  if (!old_data) {
+    BLI_assert(old_size == 0);
+    BLI_assert(*sharing_info == nullptr);
+    void *new_data = MEM_mallocN_aligned(new_size, alignment, __func__);
+    *sharing_info = info_for_mem_free(new_data);
+    return new_data;
+  }
+
+  BLI_assert(old_size != 0);
+  if ((*sharing_info)->is_mutable()) {
+    if (auto *info = dynamic_cast<MEMFreeImplicitSharing *>(*sharing_info)) {
+      /* If the array was allocated with the MEM allocator, we can use realloc directly, which
+       * could theoretically give better performance if the data can be reused in place. */
+      void *new_data = static_cast<int *>(MEM_reallocN(old_data, new_size));
+      info->data = new_data;
+      return new_data;
+    }
+  }
+
+  void *new_data = MEM_mallocN_aligned(new_size, alignment, __func__);
+  memcpy(new_data, old_data, std::min(old_size, new_size));
+  (*sharing_info)->remove_user_and_delete_if_last();
+  *sharing_info = info_for_mem_free(new_data);
+  return new_data;
+}
+
+}  // namespace detail
+
+}  // namespace blender::implicit_sharing
diff --git a/source/blender/blenloader/BLO_read_write.h b/source/blender/blenloader/BLO_read_write.h
index f1685d079e4..adf53d673e4 100644
--- a/source/blender/blenloader/BLO_read_write.h
+++ b/source/blender/blenloader/BLO_read_write.h
@@ -157,6 +157,23 @@ void blo_write_id_struct(BlendWriter *writer,
 #define BLO_write_id_struct(writer, struct_name, id_address, id) \
   blo_write_id_struct(writer, BLO_get_struct_id(writer, struct_name), id_address, id)
 
+/**
+ * Specific code to prepare IDs to be written.
+ *
+ * Required for writing properly embedded IDs currently.
+ *
+ * \note: Once there is a better generic handling of embedded IDs, this may go back to private code
+ * in writefile.c
+ */
+typedef struct BLO_Write_IDBuffer BLO_Write_IDBuffer;
+
+BLO_Write_IDBuffer *BLO_write_allocate_id_buffer(void);
+void BLO_write_init_id_buffer_from_id(BLO_Write_IDBuffer *id_buffer,
+                                      struct ID *id,
+                                      const bool is_undo);
+struct ID *BLO_write_get_id_buffer_temp_id(BLO_Write_IDBuffer *id_buffer);
+void BLO_write_destroy_id_buffer(BLO_Write_IDBuffer **id_buffer);
+
 /**
  * Write raw data.
  */
diff --git a/source/blender/blenloader/intern/readfile.cc b/source/blender/blenloader/intern/readfile.cc
index 948ade96855..77a01c6268a 100644
--- a/source/blender/blenloader/intern/readfile.cc
+++ b/source/blender/blenloader/intern/readfile.cc
@@ -2241,7 +2241,7 @@ static int lib_link_main_data_restore_cb(LibraryIDLinkCallbackData *cb_data)
 {
   const int cb_flag = cb_data->cb_flag;
   ID **id_pointer = cb_data->id_pointer;
-  if (cb_flag & IDWALK_CB_EMBEDDED || *id_pointer == nullptr) {
+  if (cb_flag & (IDWALK_CB_EMBEDDED | IDWALK_CB_EMBEDDED_NOT_OWNING) || *id_pointer == nullptr) {
     return IDWALK_RET_NOP;
   }
 
diff --git a/source/blender/blenloader/intern/versioning_280.c b/source/blender/blenloader/intern/versioning_280.c
index 77073ce2b3f..a8141e09ac9 100644
--- a/source/blender/blenloader/intern/versioning_280.c
+++ b/source/blender/blenloader/intern/versioning_280.c
@@ -1269,7 +1269,7 @@ void do_versions_after_linking_280(FileData *fd, Main *bmain)
                * it here :/ (expand element if it's the only one) */
               TreeStoreElem *tselem = BLI_mempool_calloc(space_outliner->treestore);
               tselem->type = TSE_LAYER_COLLECTION;
-              tselem->id = layer->layer_collections.first;
+              tselem->id = &((LayerCollection *)(layer->layer_collections.first))->collection->id;
               tselem->nr = tselem->used = 0;
               tselem->flag &= ~TSE_CLOSED;
             }
diff --git a/source/blender/blenloader/intern/writefile.cc b/source/blender/blenloader/intern/writefile.cc
index 0b5eb9aac51..9d04bb1759c 100644
--- a/source/blender/blenloader/intern/writefile.cc
+++ b/source/blender/blenloader/intern/writefile.cc
@@ -1088,6 +1088,78 @@ static void write_thumb(WriteData *wd, const BlendThumbnail *thumb)
 /** \name File Writing (Private)
  * \{ */
 
+#define ID_BUFFER_STATIC_SIZE 8192
+
+typedef struct BLO_Write_IDBuffer {
+  const struct IDTypeInfo *id_type;
+  ID *temp_id;
+  char id_buffer_static[ID_BUFFER_STATIC_SIZE];
+} BLO_Write_IDBuffer;
+
+static void id_buffer_init_for_id_type(BLO_Write_IDBuffer *id_buffer, const IDTypeInfo *id_type)
+{
+  if (id_type != id_buffer->id_type) {
+    const size_t idtype_struct_size = id_type->struct_size;
+    if (idtype_struct_size > ID_BUFFER_STATIC_SIZE) {
+      CLOG_ERROR(&LOG,
+                 "ID maximum buffer size (%d bytes) is not big enough to fit IDs of type %s, "
+                 "which needs %lu bytes",
+                 ID_BUFFER_STATIC_SIZE,
+                 id_type->name,
+                 idtype_struct_size);
+      id_buffer->temp_id = static_cast<ID *>(MEM_mallocN(idtype_struct_size, __func__));
+    }
+    else {
+      if (static_cast<void *>(id_buffer->temp_id) != id_buffer->id_buffer_static) {
+        MEM_SAFE_FREE(id_buffer->temp_id);
+      }
+      id_buffer->temp_id = reinterpret_cast<ID *>(id_buffer->id_buffer_static);
+    }
+    id_buffer->id_type = id_type;
+  }
+}
+
+static void id_buffer_init_from_id(BLO_Write_IDBuffer *id_buffer, ID *id, const bool is_undo)
+{
+  BLI_assert(id_buffer->id_type == BKE_idtype_get_info_from_id(id));
+
+  if (is_undo) {
+    /* Record the changes that happened up to this undo push in
+     * recalc_up_to_undo_push, and clear `recalc_after_undo_push` again
+     * to start accumulating for the next undo push. */
+    id->recalc_up_to_undo_push = id->recalc_after_undo_push;
+    id->recalc_after_undo_push = 0;
+  }
+
+  /* Copy ID data itself into buffer, to be able to freely modify it. */
+  const size_t idtype_struct_size = id_buffer->id_type->struct_size;
+  ID *temp_id = id_buffer->temp_id;
+  memcpy(temp_id, id, idtype_struct_size);
+
+  /* Clear runtime data to reduce false detection of changed data in undo/redo context. */
+  if (is_undo) {
+    temp_id->tag &= LIB_TAG_KEEP_ON_UNDO;
+  }
+  else {
+    temp_id->tag = 0;
+  }
+  temp_id->us = 0;
+  temp_id->icon_id = 0;
+  /* Those listbase data change every time we add/remove an ID, and also often when
+   * renaming one (due to re-sorting). This avoids generating a lot of false 'is changed'
+   * detections between undo steps. */
+  temp_id->prev = nullptr;
+  temp_id->next = nullptr;
+  /* Those runtime pointers should never be set during writing stage, but just in case clear
+   * them too. */
+  temp_id->orig_id = nullptr;
+  temp_id->newid = nullptr;
+  /* Even though in theory we could be able to preserve this python instance across undo even
+   * when we need to re-read the ID into its original address, this is currently cleared in
+   * #direct_link_id_common in `readfile.c` anyway. */
+  temp_id->py_instance = nullptr;
+}
+
 /* Helper callback for checking linked IDs used by given ID (assumed local), to ensure directly
  * linked data is tagged accordingly. */
 static int write_id_direct_linked_data_process_cb(LibraryIDLinkCallbackData *cb_data)
@@ -1187,11 +1259,11 @@ static bool write_file_handle(Main *mainvar,
                                                  nullptr :
                                                  BKE_lib_override_library_operations_store_init();
 
-#define ID_BUFFER_STATIC_SIZE 8192
   /* This outer loop allows to save first data-blocks from real mainvar,
    * then the temp ones from override process,
    * if needed, without duplicating whole code. */
   Main *bmain = mainvar;
+  BLO_Write_IDBuffer *id_buffer = BLO_write_allocate_id_buffer();
   do {
     ListBase *lbarray[INDEX_ID_MAX];
     int a = set_listbasepointers(bmain, lbarray);
@@ -1202,19 +1274,8 @@ static bool write_file_handle(Main *mainvar,
         continue; /* Libraries are handled separately below. */
       }
 
-      char id_buffer_static[ID_BUFFER_STATIC_SIZE];
-      void *id_buffer = id_buffer_static;
       const IDTypeInfo *id_type = BKE_idtype_get_info_from_id(id);
-      const size_t idtype_struct_size = id_type->struct_size;
-      if (idtype_struct_size > ID_BUFFER_STATIC_SIZE) {
-        CLOG_ERROR(&LOG,
-                   "ID maximum buffer size (%d bytes) is not big enough to fit IDs of type %s, "
-                   "which needs %lu bytes",
-                   ID_BUFFER_STATIC_SIZE,
-                   id_type->name,
-                   id_type->struct_size);
-        id_buffer = MEM_mallocN(idtype_struct_size, __func__);
-      }
+      id_buffer_init_for_id_type(id_buffer, id_type);
 
       for (; id; id = static_cast<ID *>(id->next)) {
         /* We should never attempt to write non-regular IDs
@@ -1249,57 +1310,12 @@ static bool write_file_handle(Main *mainvar,
           BKE_lib_override_library_operations_store_start(bmain, override_storage, id);
         }
 
-        if (wd->use_memfile) {
-          /* Record the changes that happened up to this undo push in
-           * recalc_up_to_undo_push, and clear `recalc_after_undo_push` again
-           * to start accumulating for the next undo push. */
-          id->recalc_up_to_undo_push = id->recalc_after_undo_push;
-          id->recalc_after_undo_push = 0;
-
-          bNodeTree *nodetree = ntreeFromID(id);
-          if (nodetree != nullptr) {
-            nodetree->id.recalc_up_to_undo_push = nodetree->id.recalc_after_undo_push;
-            nodetree->id.recalc_after_undo_push = 0;
-          }
-          if (GS(id->name) == ID_SCE) {
-            Scene *scene = (Scene *)id;
-            if (scene->master_collection != nullptr) {
-              scene->master_collection->id.recalc_up_to_undo_push =
-                  scene->master_collection->id.recalc_after_undo_push;
-              scene->master_collection->id.recalc_after_undo_push = 0;
-            }
-          }
-        }
-
         mywrite_id_begin(wd, id);
 
-        memcpy(id_buffer, id, idtype_struct_size);
-
-        /* Clear runtime data to reduce false detection of changed data in undo/redo context. */
-        if (wd->use_memfile) {
-          ((ID *)id_buffer)->tag &= LIB_TAG_KEEP_ON_UNDO;
-        }
-        else {
-          ((ID *)id_buffer)->tag = 0;
-        }
-        ((ID *)id_buffer)->us = 0;
-        ((ID *)id_buffer)->icon_id = 0;
-        /* Those listbase data change every time we add/remove an ID, and also often when
-         * renaming one (due to re-sorting). This avoids generating a lot of false 'is changed'
-         * detections between undo steps. */
-        ((ID *)id_buffer)->prev = nullptr;
-        ((ID *)id_buffer)->next = nullptr;
-        /* Those runtime pointers should never be set during writing stage, but just in case clear
-         * them too. */
-        ((ID *)id_buffer)->orig_id = nullptr;
-        ((ID *)id_buffer)->newid = nullptr;
-        /* Even though in theory we could be able to preserve this python instance across undo even
-         * when we need to re-read the ID into its original address, this is currently cleared in
-         * #direct_link_id_common in `readfile.c` anyway, */
-        ((ID *)id_buffer)->py_instance = nullptr;
+        id_buffer_init_from_id(id_buffer, id, wd->use_memfile);
 
         if (id_type->blend_write != nullptr) {
-          id_type->blend_write(&writer, (ID *)id_buffer, id);
+          id_type->blend_write(&writer, static_cast<ID *>(id_buffer->temp_id), id);
         }
 
         if (do_override) {
@@ -1309,14 +1325,12 @@ static bool write_file_handle(Main *mainvar,
         mywrite_id_end(wd, id);
       }
 
-      if (id_buffer != id_buffer_static) {
-        MEM_SAFE_FREE(id_buffer);
-      }
-
       mywrite_flush(wd);
     }
   } while ((bmain != override_storage) && (bmain = override_storage));
 
+  BLO_write_destroy_id_buffer(&id_buffer);
+
   if (override_storage) {
     BKE_lib_override_library_operations_store_finalize(override_storage);
     override_storage = nullptr;
@@ -1571,6 +1585,39 @@ bool BLO_write_file_mem(Main *mainvar, MemFile *compare, MemFile *current, int w
   return (err == 0);
 }
 
+/*
+ * API to handle writing IDs while clearing some of their runtime data.
+ */
+
+BLO_Write_IDBuffer *BLO_write_allocate_id_buffer()
+{
+  return MEM_cnew<BLO_Write_IDBuffer>(__func__);
+}
+
+void BLO_write_init_id_buffer_from_id(BLO_Write_IDBuffer *id_buffer, ID *id, const bool is_undo)
+{
+  const IDTypeInfo *id_type = BKE_idtype_get_info_from_id(id);
+  id_buffer_init_for_id_type(id_buffer, id_type);
+  id_buffer_init_from_id(id_buffer, id, is_undo);
+}
+
+ID *BLO_write_get_id_buffer_temp_id(BLO_Write_IDBuffer *id_buffer)
+{
+  return id_buffer->temp_id;
+}
+
+void BLO_write_destroy_id_buffer(BLO_Write_IDBuffer **id_buffer)
+{
+  if (static_cast<void *>((*id_buffer)->temp_id) != (*id_buffer)->id_buffer_static) {
+    MEM_SAFE_FREE((*id_buffer)->temp_id);
+  }
+  MEM_SAFE_FREE(*id_buffer);
+}
+
+/*
+ * API to write chunks of data.
+ */
+
 void BLO_write_raw(BlendWriter *writer, size_t size_in_bytes, const void *data_ptr)
 {
   writedata(writer->wd, BLO_CODE_DATA, size_in_bytes, data_ptr);
diff --git a/source/blender/draw/engines/gpencil/gpencil_cache_utils.c b/source/blender/draw/engines/gpencil/gpencil_cache_utils.c
index 49ddb335af8..ec67c8cfbe4 100644
--- a/source/blender/draw/engines/gpencil/gpencil_cache_utils.c
+++ b/source/blender/draw/engines/gpencil/gpencil_cache_utils.c
@@ -8,7 +8,7 @@
 #include "DRW_engine.h"
 #include "DRW_render.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_view3d.h"
 
 #include "DNA_gpencil_legacy_types.h"
diff --git a/source/blender/draw/intern/draw_attributes.cc b/source/blender/draw/intern/draw_attributes.cc
index 7d2e7a7fa2d..a6755c6adea 100644
--- a/source/blender/draw/intern/draw_attributes.cc
+++ b/source/blender/draw/intern/draw_attributes.cc
@@ -80,9 +80,10 @@ bool drw_custom_data_match_attribute(const CustomData *custom_data,
                                      int *r_layer_index,
                                      eCustomDataType *r_type)
 {
-  const eCustomDataType possible_attribute_types[8] = {
+  const eCustomDataType possible_attribute_types[9] = {
       CD_PROP_BOOL,
       CD_PROP_INT8,
+      CD_PROP_INT32_2D,
       CD_PROP_INT32,
       CD_PROP_FLOAT,
       CD_PROP_FLOAT2,
diff --git a/source/blender/draw/intern/draw_cache_impl_gpencil.cc b/source/blender/draw/intern/draw_cache_impl_gpencil.cc
index b74b2b11e76..d91809e4d23 100644
--- a/source/blender/draw/intern/draw_cache_impl_gpencil.cc
+++ b/source/blender/draw/intern/draw_cache_impl_gpencil.cc
@@ -17,7 +17,7 @@
 #include "DRW_engine.h"
 #include "DRW_render.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "GPU_batch.h"
 
 #include "DEG_depsgraph_query.h"
diff --git a/source/blender/draw/intern/draw_cache_impl_mesh.cc b/source/blender/draw/intern/draw_cache_impl_mesh.cc
index 484810bb8a8..5cc568fe2ab 100644
--- a/source/blender/draw/intern/draw_cache_impl_mesh.cc
+++ b/source/blender/draw/intern/draw_cache_impl_mesh.cc
@@ -395,6 +395,7 @@ static DRW_MeshCDMask mesh_cd_calc_used_gpu_layers(const Object *object,
         case CD_PROP_BOOL:
         case CD_PROP_INT8:
         case CD_PROP_INT32:
+        case CD_PROP_INT32_2D:
         case CD_PROP_FLOAT:
         case CD_PROP_FLOAT2: {
           if (layer != -1 && domain.has_value()) {
diff --git a/source/blender/draw/intern/draw_manager.c b/source/blender/draw/intern/draw_manager.c
index fcc79c37fe2..9ea93637b01 100644
--- a/source/blender/draw/intern/draw_manager.c
+++ b/source/blender/draw/intern/draw_manager.c
@@ -48,7 +48,7 @@
 #include "DNA_view3d_types.h"
 #include "DNA_world_types.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_screen.h"
 #include "ED_space_api.h"
 #include "ED_view3d.h"
diff --git a/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_attributes.cc b/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_attributes.cc
index 62c4273afc5..dc1c5335763 100644
--- a/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_attributes.cc
+++ b/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_attributes.cc
@@ -100,6 +100,7 @@ static uint gpu_component_size_for_attribute_type(eCustomDataType type)
        * comment #extract_attr_init. */
       return 3;
     case CD_PROP_FLOAT2:
+    case CD_PROP_INT32_2D:
       return 2;
     case CD_PROP_FLOAT3:
       return 3;
@@ -116,6 +117,7 @@ static GPUVertFetchMode get_fetch_mode_for_type(eCustomDataType type)
   switch (type) {
     case CD_PROP_INT8:
     case CD_PROP_INT32:
+    case CD_PROP_INT32_2D:
       return GPU_FETCH_INT_TO_FLOAT;
     case CD_PROP_BYTE_COLOR:
       return GPU_FETCH_INT_TO_FLOAT_UNIT;
@@ -128,6 +130,7 @@ static GPUVertCompType get_comp_type_for_type(eCustomDataType type)
 {
   switch (type) {
     case CD_PROP_INT8:
+    case CD_PROP_INT32_2D:
     case CD_PROP_INT32:
       return GPU_COMP_I32;
     case CD_PROP_BYTE_COLOR:
@@ -299,6 +302,9 @@ static void extract_attr(const MeshRenderData *mr,
     case CD_PROP_INT32:
       extract_attr_generic<int32_t, int3>(mr, vbo, request);
       break;
+    case CD_PROP_INT32_2D:
+      extract_attr_generic<int2>(mr, vbo, request);
+      break;
     case CD_PROP_FLOAT:
       extract_attr_generic<float, float3>(mr, vbo, request);
       break;
diff --git a/source/blender/editors/CMakeLists.txt b/source/blender/editors/CMakeLists.txt
index 9fff8bf861c..e13ba1768f2 100644
--- a/source/blender/editors/CMakeLists.txt
+++ b/source/blender/editors/CMakeLists.txt
@@ -12,7 +12,7 @@ if(WITH_BLENDER)
   add_subdirectory(curves)
   add_subdirectory(geometry)
   add_subdirectory(gizmo_library)
-  add_subdirectory(gpencil)
+  add_subdirectory(gpencil_legacy)
   add_subdirectory(interface)
   add_subdirectory(io)
   add_subdirectory(lattice)
diff --git a/source/blender/editors/animation/anim_channels_edit.c b/source/blender/editors/animation/anim_channels_edit.c
index e1dd1395373..4d0a2c2de42 100644
--- a/source/blender/editors/animation/anim_channels_edit.c
+++ b/source/blender/editors/animation/anim_channels_edit.c
@@ -746,7 +746,11 @@ void ANIM_frame_channel_y_extents(bContext *C, bAnimContext *ac)
 
   rctf bounds = {.xmin = FLT_MAX, .xmax = -FLT_MAX, .ymin = FLT_MAX, .ymax = -FLT_MAX};
   const bool include_handles = false;
-  const float frame_range[2] = {window_region->v2d.cur.xmin, window_region->v2d.cur.xmax};
+  float frame_range[2] = {window_region->v2d.cur.xmin, window_region->v2d.cur.xmax};
+  if (ac->scene->r.flag & SCER_PRV_RANGE) {
+    frame_range[0] = ac->scene->r.psfra;
+    frame_range[1] = ac->scene->r.pefra;
+  }
 
   LISTBASE_FOREACH (bAnimListElem *, ale, &anim_data) {
     rctf channel_bounds;
diff --git a/source/blender/editors/animation/drivers.c b/source/blender/editors/animation/drivers.c
index 3dfcd076f17..cbc8e1d5105 100644
--- a/source/blender/editors/animation/drivers.c
+++ b/source/blender/editors/animation/drivers.c
@@ -741,7 +741,7 @@ bool ANIM_driver_vars_paste(ReportList *reports, FCurve *fcu, bool replace)
 
   /* sanity checks */
   if (BLI_listbase_is_empty(&driver_vars_copybuf)) {
-    BKE_report(reports, RPT_ERROR, "No driver variables in clipboard to paste");
+    BKE_report(reports, RPT_ERROR, "No driver variables in the internal clipboard to paste");
     return false;
   }
 
@@ -1257,7 +1257,7 @@ void ANIM_OT_paste_driver_button(wmOperatorType *ot)
   /* identifiers */
   ot->name = "Paste Driver";
   ot->idname = "ANIM_OT_paste_driver_button";
-  ot->description = "Paste the driver in the clipboard to the highlighted button";
+  ot->description = "Paste the driver in the internal clipboard to the highlighted button";
 
   /* callbacks */
   ot->exec = paste_driver_button_exec;
diff --git a/source/blender/editors/armature/pose_lib_2.c b/source/blender/editors/armature/pose_lib_2.c
index 5b7ad6fb900..db490c8b32e 100644
--- a/source/blender/editors/armature/pose_lib_2.c
+++ b/source/blender/editors/armature/pose_lib_2.c
@@ -123,7 +123,7 @@ static void poselib_keytag_pose(bContext *C, Scene *scene, PoseBlendData *pbd)
   }
 
   bPose *pose = pbd->ob->pose;
-  bAction *act = pbd->act;
+  bAction *act = poselib_action_to_blend(pbd);
 
   KeyingSet *ks = ANIM_get_keyingset_for_autokeying(scene, ANIM_KS_WHOLE_CHARACTER_ID);
   ListBase dsources = {NULL, NULL};
diff --git a/source/blender/editors/armature/pose_transform.c b/source/blender/editors/armature/pose_transform.c
index 7f384c36af0..6466ecc6dac 100644
--- a/source/blender/editors/armature/pose_transform.c
+++ b/source/blender/editors/armature/pose_transform.c
@@ -798,7 +798,7 @@ static int pose_copy_exec(bContext *C, wmOperator *op)
   BLI_listbase_clear(&temp_bmain->armatures);
   BKE_main_free(temp_bmain);
   /* We are all done! */
-  BKE_report(op->reports, RPT_INFO, "Copied pose to buffer");
+  BKE_report(op->reports, RPT_INFO, "Copied pose to internal clipboard");
   return OPERATOR_FINISHED;
 }
 
@@ -807,7 +807,7 @@ void POSE_OT_copy(wmOperatorType *ot)
   /* identifiers */
   ot->name = "Copy Pose";
   ot->idname = "POSE_OT_copy";
-  ot->description = "Copies the current pose of the selected bones to copy/paste buffer";
+  ot->description = "Copy the current pose of the selected bones to the internal clipboard";
 
   /* api callbacks */
   ot->exec = pose_copy_exec;
@@ -846,13 +846,13 @@ static int pose_paste_exec(bContext *C, wmOperator *op)
 
   BLI_path_join(str, sizeof(str), BKE_tempdir_base(), "copybuffer_pose.blend");
   if (!BKE_copybuffer_read(tmp_bmain, str, op->reports, FILTER_ID_OB)) {
-    BKE_report(op->reports, RPT_ERROR, "Copy buffer is empty");
+    BKE_report(op->reports, RPT_ERROR, "Internal clipboard is empty");
     BKE_main_free(tmp_bmain);
     return OPERATOR_CANCELLED;
   }
   /* Make sure data from this file is usable for pose paste. */
   if (BLI_listbase_count_at_most(&tmp_bmain->objects, 2) != 1) {
-    BKE_report(op->reports, RPT_ERROR, "Copy buffer is not from pose mode");
+    BKE_report(op->reports, RPT_ERROR, "Internal clipboard is not from pose mode");
     BKE_main_free(tmp_bmain);
     return OPERATOR_CANCELLED;
   }
@@ -860,7 +860,7 @@ static int pose_paste_exec(bContext *C, wmOperator *op)
   Object *object_from = tmp_bmain->objects.first;
   bPose *pose_from = object_from->pose;
   if (pose_from == NULL) {
-    BKE_report(op->reports, RPT_ERROR, "Copy buffer has no pose");
+    BKE_report(op->reports, RPT_ERROR, "Internal clipboard has no pose");
     BKE_main_free(tmp_bmain);
     return OPERATOR_CANCELLED;
   }
diff --git a/source/blender/editors/gpencil/CMakeLists.txt b/source/blender/editors/gpencil_legacy/CMakeLists.txt
similarity index 91%
rename from source/blender/editors/gpencil/CMakeLists.txt
rename to source/blender/editors/gpencil_legacy/CMakeLists.txt
index af2ad0b7536..c1577b2ea60 100644
--- a/source/blender/editors/gpencil/CMakeLists.txt
+++ b/source/blender/editors/gpencil_legacy/CMakeLists.txt
@@ -77,7 +77,7 @@ if(WITH_POTRACE)
 endif()
 
 
-blender_add_lib(bf_editor_gpencil "${SRC}" "${INC}" "${INC_SYS}" "${LIB}")
+blender_add_lib(bf_editor_gpencil_legacy "${SRC}" "${INC}" "${INC_SYS}" "${LIB}")
 
 # RNA_prototypes.h
-add_dependencies(bf_editor_gpencil bf_rna)
+add_dependencies(bf_editor_gpencil_legacy bf_rna)
diff --git a/source/blender/editors/gpencil/annotate_draw.c b/source/blender/editors/gpencil_legacy/annotate_draw.c
similarity index 99%
rename from source/blender/editors/gpencil/annotate_draw.c
rename to source/blender/editors/gpencil_legacy/annotate_draw.c
index 86ced9bd5cf..49616670e15 100644
--- a/source/blender/editors/gpencil/annotate_draw.c
+++ b/source/blender/editors/gpencil_legacy/annotate_draw.c
@@ -41,7 +41,7 @@
 #include "GPU_matrix.h"
 #include "GPU_state.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_screen.h"
 #include "ED_space_api.h"
 #include "ED_view3d.h"
diff --git a/source/blender/editors/gpencil/annotate_paint.c b/source/blender/editors/gpencil_legacy/annotate_paint.c
similarity index 99%
rename from source/blender/editors/gpencil/annotate_paint.c
rename to source/blender/editors/gpencil_legacy/annotate_paint.c
index 458715ede1d..be3d4cb5883 100644
--- a/source/blender/editors/gpencil/annotate_paint.c
+++ b/source/blender/editors/gpencil_legacy/annotate_paint.c
@@ -39,7 +39,7 @@
 #include "UI_view2d.h"
 
 #include "ED_clip.h"
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_screen.h"
 #include "ED_view3d.h"
 
diff --git a/source/blender/editors/gpencil/drawgpencil.c b/source/blender/editors/gpencil_legacy/drawgpencil.c
similarity index 99%
rename from source/blender/editors/gpencil/drawgpencil.c
rename to source/blender/editors/gpencil_legacy/drawgpencil.c
index f3428d01985..113bfa75ca2 100644
--- a/source/blender/editors/gpencil/drawgpencil.c
+++ b/source/blender/editors/gpencil_legacy/drawgpencil.c
@@ -52,7 +52,7 @@
 #include "GPU_state.h"
 #include "GPU_uniform_buffer.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_screen.h"
 #include "ED_space_api.h"
 #include "ED_view3d.h"
diff --git a/source/blender/editors/gpencil/editaction_gpencil.c b/source/blender/editors/gpencil_legacy/editaction_gpencil.c
similarity index 99%
rename from source/blender/editors/gpencil/editaction_gpencil.c
rename to source/blender/editors/gpencil_legacy/editaction_gpencil.c
index ff3455f0b7d..3795b439030 100644
--- a/source/blender/editors/gpencil/editaction_gpencil.c
+++ b/source/blender/editors/gpencil_legacy/editaction_gpencil.c
@@ -24,7 +24,7 @@
 #include "BKE_report.h"
 
 #include "ED_anim_api.h"
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_keyframes_edit.h"
 #include "ED_markers.h"
 
diff --git a/source/blender/editors/gpencil/gpencil_add_blank.c b/source/blender/editors/gpencil_legacy/gpencil_add_blank.c
similarity index 98%
rename from source/blender/editors/gpencil/gpencil_add_blank.c
rename to source/blender/editors/gpencil_legacy/gpencil_add_blank.c
index d6863ccfc01..728f4fd737c 100644
--- a/source/blender/editors/gpencil/gpencil_add_blank.c
+++ b/source/blender/editors/gpencil_legacy/gpencil_add_blank.c
@@ -23,7 +23,7 @@
 
 #include "DEG_depsgraph.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 
 /* Definition of the most important info from a color */
 typedef struct ColorTemplate {
diff --git a/source/blender/editors/gpencil/gpencil_add_lineart.c b/source/blender/editors/gpencil_legacy/gpencil_add_lineart.c
similarity index 98%
rename from source/blender/editors/gpencil/gpencil_add_lineart.c
rename to source/blender/editors/gpencil_legacy/gpencil_add_lineart.c
index c3a4a8a928e..7fe07b69d21 100644
--- a/source/blender/editors/gpencil/gpencil_add_lineart.c
+++ b/source/blender/editors/gpencil_legacy/gpencil_add_lineart.c
@@ -26,7 +26,7 @@
 #include "DEG_depsgraph.h"
 #include "DEG_depsgraph_query.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 
 /* Definition of the most important info from a color */
 typedef struct ColorTemplate {
diff --git a/source/blender/editors/gpencil/gpencil_add_monkey.c b/source/blender/editors/gpencil_legacy/gpencil_add_monkey.c
similarity index 99%
rename from source/blender/editors/gpencil/gpencil_add_monkey.c
rename to source/blender/editors/gpencil_legacy/gpencil_add_monkey.c
index 6d5688230dc..998b18f86ca 100644
--- a/source/blender/editors/gpencil/gpencil_add_monkey.c
+++ b/source/blender/editors/gpencil_legacy/gpencil_add_monkey.c
@@ -23,7 +23,7 @@
 
 #include "DEG_depsgraph.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 
 void ED_gpencil_stroke_init_data(bGPDstroke *gps,
                                  const float *array,
diff --git a/source/blender/editors/gpencil/gpencil_add_stroke.c b/source/blender/editors/gpencil_legacy/gpencil_add_stroke.c
similarity index 99%
rename from source/blender/editors/gpencil/gpencil_add_stroke.c
rename to source/blender/editors/gpencil_legacy/gpencil_add_stroke.c
index 652c9ff6c8b..41af24773e0 100644
--- a/source/blender/editors/gpencil/gpencil_add_stroke.c
+++ b/source/blender/editors/gpencil_legacy/gpencil_add_stroke.c
@@ -23,7 +23,7 @@
 
 #include "DEG_depsgraph.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 
 /* Definition of the most important info from a color */
 typedef struct ColorTemplate {
diff --git a/source/blender/editors/gpencil/gpencil_armature.c b/source/blender/editors/gpencil_legacy/gpencil_armature.c
similarity index 99%
rename from source/blender/editors/gpencil/gpencil_armature.c
rename to source/blender/editors/gpencil_legacy/gpencil_armature.c
index c38a0ef7bef..43cf338f129 100644
--- a/source/blender/editors/gpencil/gpencil_armature.c
+++ b/source/blender/editors/gpencil_legacy/gpencil_armature.c
@@ -41,7 +41,7 @@
 #include "RNA_define.h"
 #include "RNA_enum_types.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_mesh.h"
 #include "ED_object.h"
 
diff --git a/source/blender/editors/gpencil/gpencil_bake_animation.cc b/source/blender/editors/gpencil_legacy/gpencil_bake_animation.cc
similarity index 99%
rename from source/blender/editors/gpencil/gpencil_bake_animation.cc
rename to source/blender/editors/gpencil_legacy/gpencil_bake_animation.cc
index b2b639a9cc9..ce9afb362c4 100644
--- a/source/blender/editors/gpencil/gpencil_bake_animation.cc
+++ b/source/blender/editors/gpencil_legacy/gpencil_bake_animation.cc
@@ -39,7 +39,7 @@
 #include "RNA_access.h"
 #include "RNA_define.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_transform_snap_object_context.h"
 
 #include "gpencil_intern.h"
diff --git a/source/blender/editors/gpencil/gpencil_convert.c b/source/blender/editors/gpencil_legacy/gpencil_convert.c
similarity index 99%
rename from source/blender/editors/gpencil/gpencil_convert.c
rename to source/blender/editors/gpencil_legacy/gpencil_convert.c
index 2641d1903c5..97763060269 100644
--- a/source/blender/editors/gpencil/gpencil_convert.c
+++ b/source/blender/editors/gpencil_legacy/gpencil_convert.c
@@ -65,7 +65,7 @@
 #include "UI_view2d.h"
 
 #include "ED_clip.h"
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_keyframing.h"
 #include "ED_object.h"
 #include "ED_view3d.h"
diff --git a/source/blender/editors/gpencil/gpencil_data.c b/source/blender/editors/gpencil_legacy/gpencil_data.c
similarity index 99%
rename from source/blender/editors/gpencil/gpencil_data.c
rename to source/blender/editors/gpencil_legacy/gpencil_data.c
index be89e63c9c5..32368022afe 100644
--- a/source/blender/editors/gpencil/gpencil_data.c
+++ b/source/blender/editors/gpencil_legacy/gpencil_data.c
@@ -62,7 +62,7 @@
 #include "RNA_define.h"
 #include "RNA_enum_types.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_object.h"
 
 #include "DEG_depsgraph.h"
diff --git a/source/blender/editors/gpencil/gpencil_edit.c b/source/blender/editors/gpencil_legacy/gpencil_edit.c
similarity index 99%
rename from source/blender/editors/gpencil/gpencil_edit.c
rename to source/blender/editors/gpencil_legacy/gpencil_edit.c
index f832ca337b2..566777a4a12 100644
--- a/source/blender/editors/gpencil/gpencil_edit.c
+++ b/source/blender/editors/gpencil_legacy/gpencil_edit.c
@@ -66,7 +66,7 @@
 #include "UI_view2d.h"
 
 #include "ED_armature.h"
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_keyframing.h"
 #include "ED_object.h"
 #include "ED_outliner.h"
diff --git a/source/blender/editors/gpencil/gpencil_edit_curve.c b/source/blender/editors/gpencil_legacy/gpencil_edit_curve.c
similarity index 99%
rename from source/blender/editors/gpencil/gpencil_edit_curve.c
rename to source/blender/editors/gpencil_legacy/gpencil_edit_curve.c
index 338072d15c8..26890004238 100644
--- a/source/blender/editors/gpencil/gpencil_edit_curve.c
+++ b/source/blender/editors/gpencil_legacy/gpencil_edit_curve.c
@@ -29,7 +29,7 @@
 #include "WM_api.h"
 #include "WM_types.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 
 #include "DEG_depsgraph.h"
 
diff --git a/source/blender/editors/gpencil/gpencil_fill.c b/source/blender/editors/gpencil_legacy/gpencil_fill.c
similarity index 99%
rename from source/blender/editors/gpencil/gpencil_fill.c
rename to source/blender/editors/gpencil_legacy/gpencil_fill.c
index 397f4d7c924..d618cc9fece 100644
--- a/source/blender/editors/gpencil/gpencil_fill.c
+++ b/source/blender/editors/gpencil_legacy/gpencil_fill.c
@@ -38,7 +38,7 @@
 #include "BKE_report.h"
 #include "BKE_screen.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_keyframing.h"
 #include "ED_screen.h"
 #include "ED_space_api.h"
diff --git a/source/blender/editors/gpencil/gpencil_intern.h b/source/blender/editors/gpencil_legacy/gpencil_intern.h
similarity index 100%
rename from source/blender/editors/gpencil/gpencil_intern.h
rename to source/blender/editors/gpencil_legacy/gpencil_intern.h
diff --git a/source/blender/editors/gpencil/gpencil_interpolate.c b/source/blender/editors/gpencil_legacy/gpencil_interpolate.c
similarity index 99%
rename from source/blender/editors/gpencil/gpencil_interpolate.c
rename to source/blender/editors/gpencil_legacy/gpencil_interpolate.c
index c8714ce8e8e..6b08b8b6e3c 100644
--- a/source/blender/editors/gpencil/gpencil_interpolate.c
+++ b/source/blender/editors/gpencil_legacy/gpencil_interpolate.c
@@ -47,7 +47,7 @@
 #include "RNA_define.h"
 #include "RNA_prototypes.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_screen.h"
 
 #include "DEG_depsgraph.h"
diff --git a/source/blender/editors/gpencil/gpencil_merge.c b/source/blender/editors/gpencil_legacy/gpencil_merge.c
similarity index 99%
rename from source/blender/editors/gpencil/gpencil_merge.c
rename to source/blender/editors/gpencil_legacy/gpencil_merge.c
index 24966ea5d7f..0c63697f2a1 100644
--- a/source/blender/editors/gpencil/gpencil_merge.c
+++ b/source/blender/editors/gpencil_legacy/gpencil_merge.c
@@ -31,7 +31,7 @@
 #include "RNA_access.h"
 #include "RNA_define.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_screen.h"
 
 #include "DEG_depsgraph.h"
diff --git a/source/blender/editors/gpencil/gpencil_mesh.cc b/source/blender/editors/gpencil_legacy/gpencil_mesh.cc
similarity index 99%
rename from source/blender/editors/gpencil/gpencil_mesh.cc
rename to source/blender/editors/gpencil_legacy/gpencil_mesh.cc
index 9ad00ef174e..9cef4f42e97 100644
--- a/source/blender/editors/gpencil/gpencil_mesh.cc
+++ b/source/blender/editors/gpencil_legacy/gpencil_mesh.cc
@@ -37,7 +37,7 @@
 #include "RNA_access.h"
 #include "RNA_define.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_transform_snap_object_context.h"
 
 #include "gpencil_intern.h"
diff --git a/source/blender/editors/gpencil/gpencil_ops.c b/source/blender/editors/gpencil_legacy/gpencil_ops.c
similarity index 99%
rename from source/blender/editors/gpencil/gpencil_ops.c
rename to source/blender/editors/gpencil_legacy/gpencil_ops.c
index 43d82de79dc..b534928999d 100644
--- a/source/blender/editors/gpencil/gpencil_ops.c
+++ b/source/blender/editors/gpencil_legacy/gpencil_ops.c
@@ -26,7 +26,7 @@
 
 #include "RNA_access.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 
 #include "gpencil_intern.h"
 
diff --git a/source/blender/editors/gpencil/gpencil_ops_versioning.c b/source/blender/editors/gpencil_legacy/gpencil_ops_versioning.c
similarity index 99%
rename from source/blender/editors/gpencil/gpencil_ops_versioning.c
rename to source/blender/editors/gpencil_legacy/gpencil_ops_versioning.c
index 9c85754f3bd..7fa8a9d73ed 100644
--- a/source/blender/editors/gpencil/gpencil_ops_versioning.c
+++ b/source/blender/editors/gpencil_legacy/gpencil_ops_versioning.c
@@ -32,7 +32,7 @@
 #include "RNA_access.h"
 #include "RNA_define.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 
 #include "DEG_depsgraph.h"
 #include "DEG_depsgraph_query.h"
diff --git a/source/blender/editors/gpencil/gpencil_paint.c b/source/blender/editors/gpencil_legacy/gpencil_paint.c
similarity index 99%
rename from source/blender/editors/gpencil/gpencil_paint.c
rename to source/blender/editors/gpencil_legacy/gpencil_paint.c
index d4ec1ba76ae..aeb74980935 100644
--- a/source/blender/editors/gpencil/gpencil_paint.c
+++ b/source/blender/editors/gpencil_legacy/gpencil_paint.c
@@ -52,7 +52,7 @@
 #include "UI_view2d.h"
 
 #include "ED_clip.h"
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_keyframing.h"
 #include "ED_object.h"
 #include "ED_screen.h"
diff --git a/source/blender/editors/gpencil/gpencil_primitive.c b/source/blender/editors/gpencil_legacy/gpencil_primitive.c
similarity index 99%
rename from source/blender/editors/gpencil/gpencil_primitive.c
rename to source/blender/editors/gpencil_legacy/gpencil_primitive.c
index c33f2675a91..004d6d4d9ef 100644
--- a/source/blender/editors/gpencil/gpencil_primitive.c
+++ b/source/blender/editors/gpencil_legacy/gpencil_primitive.c
@@ -54,7 +54,7 @@
 #include "RNA_define.h"
 #include "RNA_enum_types.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_keyframing.h"
 #include "ED_object.h"
 #include "ED_screen.h"
diff --git a/source/blender/editors/gpencil/gpencil_sculpt_paint.c b/source/blender/editors/gpencil_legacy/gpencil_sculpt_paint.c
similarity index 99%
rename from source/blender/editors/gpencil/gpencil_sculpt_paint.c
rename to source/blender/editors/gpencil_legacy/gpencil_sculpt_paint.c
index 7ced965fa04..f6659c4e2cd 100644
--- a/source/blender/editors/gpencil/gpencil_sculpt_paint.c
+++ b/source/blender/editors/gpencil_legacy/gpencil_sculpt_paint.c
@@ -58,7 +58,7 @@
 
 #include "UI_view2d.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_keyframing.h"
 #include "ED_screen.h"
 #include "ED_view3d.h"
diff --git a/source/blender/editors/gpencil/gpencil_select.c b/source/blender/editors/gpencil_legacy/gpencil_select.c
similarity index 99%
rename from source/blender/editors/gpencil/gpencil_select.c
rename to source/blender/editors/gpencil_legacy/gpencil_select.c
index fd3effc144a..ed7093a8f35 100644
--- a/source/blender/editors/gpencil/gpencil_select.c
+++ b/source/blender/editors/gpencil_legacy/gpencil_select.c
@@ -45,7 +45,7 @@
 
 #include "UI_view2d.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_select_utils.h"
 #include "ED_view3d.h"
 
diff --git a/source/blender/editors/gpencil/gpencil_trace.h b/source/blender/editors/gpencil_legacy/gpencil_trace.h
similarity index 100%
rename from source/blender/editors/gpencil/gpencil_trace.h
rename to source/blender/editors/gpencil_legacy/gpencil_trace.h
diff --git a/source/blender/editors/gpencil/gpencil_trace_ops.c b/source/blender/editors/gpencil_legacy/gpencil_trace_ops.c
similarity index 99%
rename from source/blender/editors/gpencil/gpencil_trace_ops.c
rename to source/blender/editors/gpencil_legacy/gpencil_trace_ops.c
index 6b3a71b557d..fd7e13f70a8 100644
--- a/source/blender/editors/gpencil/gpencil_trace_ops.c
+++ b/source/blender/editors/gpencil_legacy/gpencil_trace_ops.c
@@ -36,7 +36,7 @@
 
 #include "IMB_imbuf_types.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_object.h"
 
 #include "gpencil_intern.h"
diff --git a/source/blender/editors/gpencil/gpencil_trace_utils.c b/source/blender/editors/gpencil_legacy/gpencil_trace_utils.c
similarity index 100%
rename from source/blender/editors/gpencil/gpencil_trace_utils.c
rename to source/blender/editors/gpencil_legacy/gpencil_trace_utils.c
diff --git a/source/blender/editors/gpencil/gpencil_undo.cc b/source/blender/editors/gpencil_legacy/gpencil_undo.cc
similarity index 99%
rename from source/blender/editors/gpencil/gpencil_undo.cc
rename to source/blender/editors/gpencil_legacy/gpencil_undo.cc
index 566e9c3033f..380cf959ed4 100644
--- a/source/blender/editors/gpencil/gpencil_undo.cc
+++ b/source/blender/editors/gpencil_legacy/gpencil_undo.cc
@@ -22,7 +22,7 @@
 #include "BKE_gpencil_legacy.h"
 #include "BKE_undo_system.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 
 #include "WM_api.h"
 #include "WM_types.h"
diff --git a/source/blender/editors/gpencil/gpencil_utils.c b/source/blender/editors/gpencil_legacy/gpencil_utils.c
similarity index 99%
rename from source/blender/editors/gpencil/gpencil_utils.c
rename to source/blender/editors/gpencil_legacy/gpencil_utils.c
index fef369427ad..34da7c160c4 100644
--- a/source/blender/editors/gpencil/gpencil_utils.c
+++ b/source/blender/editors/gpencil_legacy/gpencil_utils.c
@@ -63,7 +63,7 @@
 #include "UI_view2d.h"
 
 #include "ED_clip.h"
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_object.h"
 #include "ED_screen.h"
 #include "ED_select_utils.h"
diff --git a/source/blender/editors/gpencil/gpencil_uv.c b/source/blender/editors/gpencil_legacy/gpencil_uv.c
similarity index 99%
rename from source/blender/editors/gpencil/gpencil_uv.c
rename to source/blender/editors/gpencil_legacy/gpencil_uv.c
index 2b9390a1beb..bed0b5ba295 100644
--- a/source/blender/editors/gpencil/gpencil_uv.c
+++ b/source/blender/editors/gpencil_legacy/gpencil_uv.c
@@ -26,7 +26,7 @@
 
 #include "UI_interface.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_numinput.h"
 #include "ED_screen.h"
 #include "ED_space_api.h"
diff --git a/source/blender/editors/gpencil/gpencil_vertex_ops.c b/source/blender/editors/gpencil_legacy/gpencil_vertex_ops.c
similarity index 99%
rename from source/blender/editors/gpencil/gpencil_vertex_ops.c
rename to source/blender/editors/gpencil_legacy/gpencil_vertex_ops.c
index 4fe87a51b93..d040d4fa8b9 100644
--- a/source/blender/editors/gpencil/gpencil_vertex_ops.c
+++ b/source/blender/editors/gpencil_legacy/gpencil_vertex_ops.c
@@ -28,7 +28,7 @@
 #include "RNA_access.h"
 #include "RNA_define.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_screen.h"
 
 #include "DEG_depsgraph.h"
diff --git a/source/blender/editors/gpencil/gpencil_vertex_paint.c b/source/blender/editors/gpencil_legacy/gpencil_vertex_paint.c
similarity index 99%
rename from source/blender/editors/gpencil/gpencil_vertex_paint.c
rename to source/blender/editors/gpencil_legacy/gpencil_vertex_paint.c
index 3e96f406fd5..ce21976c7c2 100644
--- a/source/blender/editors/gpencil/gpencil_vertex_paint.c
+++ b/source/blender/editors/gpencil_legacy/gpencil_vertex_paint.c
@@ -33,7 +33,7 @@
 
 #include "UI_view2d.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_screen.h"
 #include "ED_view3d.h"
 
diff --git a/source/blender/editors/gpencil/gpencil_weight_paint.c b/source/blender/editors/gpencil_legacy/gpencil_weight_paint.c
similarity index 99%
rename from source/blender/editors/gpencil/gpencil_weight_paint.c
rename to source/blender/editors/gpencil_legacy/gpencil_weight_paint.c
index 85aa9e3a3d7..2bd827969bb 100644
--- a/source/blender/editors/gpencil/gpencil_weight_paint.c
+++ b/source/blender/editors/gpencil_legacy/gpencil_weight_paint.c
@@ -38,7 +38,7 @@
 
 #include "UI_view2d.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_screen.h"
 #include "ED_view3d.h"
 
diff --git a/source/blender/editors/include/ED_gpencil.h b/source/blender/editors/include/ED_gpencil_legacy.h
similarity index 100%
rename from source/blender/editors/include/ED_gpencil.h
rename to source/blender/editors/include/ED_gpencil_legacy.h
diff --git a/source/blender/editors/interface/eyedroppers/eyedropper_gpencil_color.cc b/source/blender/editors/interface/eyedroppers/eyedropper_gpencil_color.cc
index 20592636fe7..187902c46ff 100644
--- a/source/blender/editors/interface/eyedroppers/eyedropper_gpencil_color.cc
+++ b/source/blender/editors/interface/eyedroppers/eyedropper_gpencil_color.cc
@@ -39,7 +39,7 @@
 #include "RNA_access.h"
 #include "RNA_define.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_screen.h"
 #include "ED_undo.h"
 
diff --git a/source/blender/editors/interface/interface_ops.cc b/source/blender/editors/interface/interface_ops.cc
index 0d52993a47a..e133e54fea7 100644
--- a/source/blender/editors/interface/interface_ops.cc
+++ b/source/blender/editors/interface/interface_ops.cc
@@ -245,8 +245,8 @@ static void UI_OT_copy_as_driver_button(wmOperatorType *ot)
   ot->idname = "UI_OT_copy_as_driver_button";
   ot->description =
       "Create a new driver with this property as input, and copy it to the "
-      "clipboard. Use Paste Driver to add it to the target property, or Paste "
-      "Driver Variables to extend an existing driver";
+      "internal clipboard. Use Paste Driver to add it to the target property, "
+      "or Paste Driver Variables to extend an existing driver";
 
   /* callbacks */
   ot->exec = copy_as_driver_button_exec;
diff --git a/source/blender/editors/interface/interface_query.cc b/source/blender/editors/interface/interface_query.cc
index 8597dd1b279..562c05df77f 100644
--- a/source/blender/editors/interface/interface_query.cc
+++ b/source/blender/editors/interface/interface_query.cc
@@ -155,10 +155,16 @@ bool UI_but_is_tool(const uiBut *but)
 
 bool UI_but_has_tooltip_label(const uiBut *but)
 {
-  if ((but->drawstr[0] == '\0') && !ui_block_is_popover(but->block)) {
-    return UI_but_is_tool(but);
+  /* No tooltip label if the button itself shows a label already. */
+  if (but->drawstr[0] != '\0') {
+    return false;
   }
-  return false;
+
+  if (UI_but_is_tool(but)) {
+    return !ui_block_is_popover(but->block);
+  }
+
+  return ELEM(but->type, UI_BTYPE_TAB);
 }
 
 int ui_but_icon(const uiBut *but)
diff --git a/source/blender/editors/interface/interface_region_tooltip.cc b/source/blender/editors/interface/interface_region_tooltip.cc
index fd5fcbefd60..e5e216c8cfc 100644
--- a/source/blender/editors/interface/interface_region_tooltip.cc
+++ b/source/blender/editors/interface/interface_region_tooltip.cc
@@ -742,7 +742,8 @@ static uiTooltipData *ui_tooltip_data_from_tool(bContext *C, uiBut *but, bool is
 
 static uiTooltipData *ui_tooltip_data_from_button_or_extra_icon(bContext *C,
                                                                 uiBut *but,
-                                                                uiButExtraOpIcon *extra_icon)
+                                                                uiButExtraOpIcon *extra_icon,
+                                                                const bool is_label)
 {
   uiStringInfo but_label = {BUT_GET_LABEL, nullptr};
   uiStringInfo but_tip = {BUT_GET_TIP, nullptr};
@@ -763,20 +764,30 @@ static uiTooltipData *ui_tooltip_data_from_button_or_extra_icon(bContext *C,
   uiTooltipData *data = MEM_cnew<uiTooltipData>(__func__);
 
   if (extra_icon) {
-    UI_but_extra_icon_string_info_get(C, extra_icon, &but_label, &but_tip, &op_keymap, nullptr);
+    if (is_label) {
+      UI_but_extra_icon_string_info_get(C, extra_icon, &but_label, &enum_label, nullptr);
+    }
+    else {
+      UI_but_extra_icon_string_info_get(C, extra_icon, &but_label, &but_tip, &op_keymap, nullptr);
+    }
   }
   else {
-    UI_but_string_info_get(C,
-                           but,
-                           &but_label,
-                           &but_tip,
-                           &enum_label,
-                           &enum_tip,
-                           &op_keymap,
-                           &prop_keymap,
-                           &rna_struct,
-                           &rna_prop,
-                           nullptr);
+    if (is_label) {
+      UI_but_string_info_get(C, but, &but_label, &enum_label, nullptr);
+    }
+    else {
+      UI_but_string_info_get(C,
+                             but,
+                             &but_label,
+                             &but_tip,
+                             &enum_label,
+                             &enum_tip,
+                             &op_keymap,
+                             &prop_keymap,
+                             &rna_struct,
+                             &rna_prop,
+                             nullptr);
+    }
   }
 
   /* Tip Label (only for buttons not already showing the label).
@@ -811,6 +822,13 @@ static uiTooltipData *ui_tooltip_data_from_button_or_extra_icon(bContext *C,
       field->text = BLI_strdup(TIP_("(Shift-Click/Drag to select multiple)"));
     }
   }
+  /* When there is only an enum label (no button label or tip), draw that as header. */
+  else if (enum_label.strinfo && !(but_label.strinfo && but_label.strinfo[0])) {
+    uiTooltipField *field = text_field_add(
+        data, uiTooltipFormat::Style::Header, uiTooltipFormat::ColorID::Normal);
+    field->text = BLI_strdup(enum_label.strinfo);
+  }
+
   /* Enum field label & tip. */
   if (enum_tip.strinfo) {
     uiTooltipField *field = text_field_add(
@@ -1346,11 +1364,11 @@ ARegion *UI_tooltip_create_from_button_or_extra_icon(
   }
 
   if (data == nullptr) {
-    data = ui_tooltip_data_from_button_or_extra_icon(C, but, extra_icon);
+    data = ui_tooltip_data_from_button_or_extra_icon(C, but, extra_icon, is_label);
   }
 
   if (data == nullptr) {
-    data = ui_tooltip_data_from_button_or_extra_icon(C, but, nullptr);
+    data = ui_tooltip_data_from_button_or_extra_icon(C, but, nullptr, is_label);
   }
 
   if (data == nullptr) {
diff --git a/source/blender/editors/io/io_gpencil_import.c b/source/blender/editors/io/io_gpencil_import.c
index a9a28978052..91c719849cc 100644
--- a/source/blender/editors/io/io_gpencil_import.c
+++ b/source/blender/editors/io/io_gpencil_import.c
@@ -32,7 +32,7 @@
 #  include "DEG_depsgraph.h"
 #  include "DEG_depsgraph_query.h"
 
-#  include "ED_gpencil.h"
+#  include "ED_gpencil_legacy.h"
 
 #  include "io_gpencil.h"
 
diff --git a/source/blender/editors/io/io_usd.c b/source/blender/editors/io/io_usd.c
index f1ac579d6bc..7e352cef0a3 100644
--- a/source/blender/editors/io/io_usd.c
+++ b/source/blender/editors/io/io_usd.c
@@ -326,7 +326,7 @@ void WM_OT_usd_export(struct wmOperatorType *ot)
                   "overwrite_textures",
                   false,
                   "Overwrite Textures",
-                  "Allow overwriting existing texture files when exporting textures");
+                  "Overwrite existing files when exporting textures");
 
   RNA_def_boolean(ot->srna,
                   "relative_paths",
@@ -612,7 +612,7 @@ void WM_OT_usd_import(struct wmOperatorType *ot)
   RNA_def_boolean(ot->srna, "read_mesh_uvs", true, "UV Coordinates", "Read mesh UV coordinates");
 
   RNA_def_boolean(
-      ot->srna, "read_mesh_colors", false, "Color Attributes", "Read mesh color attributes");
+      ot->srna, "read_mesh_colors", true, "Color Attributes", "Read mesh color attributes");
 
   RNA_def_string(ot->srna,
                  "prim_path_mask",
diff --git a/source/blender/editors/mask/mask_ops.c b/source/blender/editors/mask/mask_ops.c
index fcabc1bc1ec..58b3b07e1be 100644
--- a/source/blender/editors/mask/mask_ops.c
+++ b/source/blender/editors/mask/mask_ops.c
@@ -2069,7 +2069,7 @@ void MASK_OT_copy_splines(wmOperatorType *ot)
 {
   /* identifiers */
   ot->name = "Copy Splines";
-  ot->description = "Copy selected splines to clipboard";
+  ot->description = "Copy the selected splines to the internal clipboard";
   ot->idname = "MASK_OT_copy_splines";
 
   /* api callbacks */
@@ -2113,7 +2113,7 @@ void MASK_OT_paste_splines(wmOperatorType *ot)
 {
   /* identifiers */
   ot->name = "Paste Splines";
-  ot->description = "Paste splines from clipboard";
+  ot->description = "Paste splines from the internal clipboard";
   ot->idname = "MASK_OT_paste_splines";
 
   /* api callbacks */
diff --git a/source/blender/editors/mesh/editmesh_attribute.cc b/source/blender/editors/mesh/editmesh_attribute.cc
index f9a8d551abd..8385c6194d6 100644
--- a/source/blender/editors/mesh/editmesh_attribute.cc
+++ b/source/blender/editors/mesh/editmesh_attribute.cc
@@ -102,6 +102,8 @@ static StringRefNull rna_property_name_for_type(const eCustomDataType type)
     case CD_PROP_INT8:
     case CD_PROP_INT32:
       return "value_int";
+    case CD_PROP_INT32_2D:
+      return "value_int_vector_2d";
     default:
       BLI_assert_unreachable();
       return "";
@@ -208,6 +210,9 @@ static int mesh_set_attribute_exec(bContext *C, wmOperator *op)
     case CD_PROP_INT32:
       *static_cast<int32_t *>(buffer) = RNA_int_get(op->ptr, prop_name.c_str());
       break;
+    case CD_PROP_INT32_2D:
+      RNA_int_get_array(op->ptr, prop_name.c_str(), static_cast<int *>(buffer));
+      break;
     default:
       BLI_assert_unreachable();
   }
@@ -320,6 +325,9 @@ static int mesh_set_attribute_invoke(bContext *C, wmOperator *op, const wmEvent
       case CD_PROP_INT32:
         RNA_property_int_set(op->ptr, prop, *active_value.get<int32_t>());
         break;
+      case CD_PROP_INT32_2D:
+        RNA_property_int_set_array(op->ptr, prop, *active_value.get<int2>());
+        break;
       default:
         BLI_assert_unreachable();
     }
@@ -385,6 +393,16 @@ void MESH_OT_attribute_set(wmOperatorType *ot)
                       -FLT_MAX,
                       FLT_MAX);
   RNA_def_int(ot->srna, "value_int", 0, INT_MIN, INT_MAX, "Value", "", INT_MIN, INT_MAX);
+  RNA_def_int_array(ot->srna,
+                    "value_int_vector_2d",
+                    2,
+                    nullptr,
+                    INT_MIN,
+                    INT_MAX,
+                    "Value",
+                    "",
+                    INT_MIN,
+                    INT_MAX);
   RNA_def_float_color(
       ot->srna, "value_color", 4, color_default, -FLT_MAX, FLT_MAX, "Value", "", 0.0f, 1.0f);
   RNA_def_boolean(ot->srna, "value_bool", false, "Value", "");
diff --git a/source/blender/editors/mesh/editmesh_tools.cc b/source/blender/editors/mesh/editmesh_tools.cc
index e17c5db1278..7411bd4a4f8 100644
--- a/source/blender/editors/mesh/editmesh_tools.cc
+++ b/source/blender/editors/mesh/editmesh_tools.cc
@@ -9370,8 +9370,12 @@ enum {
 };
 
 static EnumPropertyItem normal_vector_tool_items[] = {
-    {EDBM_CLNOR_TOOLS_COPY, "COPY", 0, "Copy Normal", "Copy normal to buffer"},
-    {EDBM_CLNOR_TOOLS_PASTE, "PASTE", 0, "Paste Normal", "Paste normal from buffer"},
+    {EDBM_CLNOR_TOOLS_COPY, "COPY", 0, "Copy Normal", "Copy normal to the internal clipboard"},
+    {EDBM_CLNOR_TOOLS_PASTE,
+     "PASTE",
+     0,
+     "Paste Normal",
+     "Paste normal from the internal clipboard"},
     {EDBM_CLNOR_TOOLS_ADD, "ADD", 0, "Add Normal", "Add normal vector with selection"},
     {EDBM_CLNOR_TOOLS_MULTIPLY,
      "MULTIPLY",
@@ -9382,7 +9386,7 @@ static EnumPropertyItem normal_vector_tool_items[] = {
      "RESET",
      0,
      "Reset Normal",
-     "Reset buffer and/or normal of selected element"},
+     "Reset the internal clipboard and/or normal of selected element"},
     {0, nullptr, 0, nullptr, nullptr},
 };
 
diff --git a/source/blender/editors/mesh/editmesh_undo.cc b/source/blender/editors/mesh/editmesh_undo.cc
index 098a4ef48ee..f8e5a4367d6 100644
--- a/source/blender/editors/mesh/editmesh_undo.cc
+++ b/source/blender/editors/mesh/editmesh_undo.cc
@@ -408,8 +408,8 @@ static void um_arraystore_compact_ex(UndoMesh *um, const UndoMesh *um_ref, bool
             um->store.poly_offset_indices = BLI_array_store_state_add(
                 bs, me->poly_offset_indices, size_t(me->totpoly + 1) * stride, state_reference);
           }
-
-          MEM_SAFE_FREE(me->poly_offset_indices);
+          blender::implicit_sharing::free_shared_data(&me->poly_offset_indices,
+                                                      &me->runtime->poly_offsets_sharing_info);
         }
       },
       [&]() {
@@ -577,6 +577,8 @@ static void um_arraystore_expand(UndoMesh *um)
     size_t state_len;
     me->poly_offset_indices = static_cast<int *>(
         BLI_array_store_state_data_get_alloc(state, &state_len));
+    me->runtime->poly_offsets_sharing_info = blender::implicit_sharing::info_for_mem_free(
+        me->poly_offset_indices);
     BLI_assert((me->totpoly + 1) == (state_len / stride));
     UNUSED_VARS_NDEBUG(stride);
   }
diff --git a/source/blender/editors/mesh/mesh_data.cc b/source/blender/editors/mesh/mesh_data.cc
index ce417294187..fc54a974d60 100644
--- a/source/blender/editors/mesh/mesh_data.cc
+++ b/source/blender/editors/mesh/mesh_data.cc
@@ -1251,8 +1251,13 @@ static void mesh_add_polys(Mesh *mesh, int len)
   CustomData_copy_layout(&mesh->pdata, &pdata, CD_MASK_MESH.pmask, CD_SET_DEFAULT, totpoly);
   CustomData_copy_data(&mesh->pdata, &pdata, 0, 0, mesh->totpoly);
 
-  mesh->poly_offset_indices = static_cast<int *>(
-      MEM_reallocN(mesh->poly_offset_indices, sizeof(int) * (totpoly + 1)));
+  implicit_sharing::resize_trivial_array(&mesh->poly_offset_indices,
+                                         &mesh->runtime->poly_offsets_sharing_info,
+                                         mesh->totpoly == 0 ? 0 : (mesh->totpoly + 1),
+                                         totpoly + 1);
+  /* Set common values for convenience. */
+  mesh->poly_offset_indices[0] = 0;
+  mesh->poly_offset_indices[totpoly] = mesh->totloop;
 
   CustomData_free(&mesh->pdata, mesh->totpoly);
   mesh->pdata = pdata;
@@ -1260,9 +1265,6 @@ static void mesh_add_polys(Mesh *mesh, int len)
   BKE_mesh_runtime_clear_cache(mesh);
 
   mesh->totpoly = totpoly;
-  /* Update the last offset, which may not be set elsewhere and must be the same as the number of
-   * face corners. */
-  mesh->poly_offsets_for_write().last() = mesh->totloop;
 
   bke::MutableAttributeAccessor attributes = mesh->attributes_for_write();
   bke::SpanAttributeWriter<bool> select_poly = attributes.lookup_or_add_for_write_span<bool>(
diff --git a/source/blender/editors/mesh/meshtools.cc b/source/blender/editors/mesh/meshtools.cc
index 021d77fa152..de6d40b5fea 100644
--- a/source/blender/editors/mesh/meshtools.cc
+++ b/source/blender/editors/mesh/meshtools.cc
@@ -677,7 +677,11 @@ int ED_mesh_join_objects_exec(bContext *C, wmOperator *op)
 
   BKE_mesh_clear_geometry(me);
 
-  me->poly_offset_indices = poly_offsets;
+  if (totpoly) {
+    me->poly_offset_indices = poly_offsets;
+    me->runtime->poly_offsets_sharing_info = blender::implicit_sharing::info_for_mem_free(
+        poly_offsets);
+  }
 
   me->totvert = totvert;
   me->totedge = totedge;
diff --git a/source/blender/editors/object/CMakeLists.txt b/source/blender/editors/object/CMakeLists.txt
index 3b7318de032..9ed1f7046b7 100644
--- a/source/blender/editors/object/CMakeLists.txt
+++ b/source/blender/editors/object/CMakeLists.txt
@@ -9,7 +9,7 @@ set(INC
   ../../bmesh
   ../../depsgraph
   ../../functions
-  ../../gpencil_modifiers
+  ../../gpencil_modifiers_legacy
   ../../gpu
   ../../ikplugin
   ../../imbuf
diff --git a/source/blender/editors/object/object_add.cc b/source/blender/editors/object/object_add.cc
index 5fe5a401fca..34d83e9118d 100644
--- a/source/blender/editors/object/object_add.cc
+++ b/source/blender/editors/object/object_add.cc
@@ -100,7 +100,7 @@
 #include "ED_armature.h"
 #include "ED_curve.h"
 #include "ED_curves.h"
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_mball.h"
 #include "ED_mesh.h"
 #include "ED_node.h"
@@ -3384,6 +3384,9 @@ static int object_convert_exec(bContext *C, wmOperator *op)
       }
 
       Mesh *new_mesh = static_cast<Mesh *>(BKE_id_new(bmain, ID_ME, newob->id.name + 2));
+      newob->data = new_mesh;
+      newob->type = OB_MESH;
+
       if (const Mesh *mesh_eval = geometry.get_mesh_for_read()) {
         BKE_mesh_nomain_to_mesh(BKE_mesh_copy_for_eval(mesh_eval, false), new_mesh, newob);
         BKE_object_material_from_eval_data(bmain, newob, &mesh_eval->id);
@@ -3393,6 +3396,9 @@ static int object_convert_exec(bContext *C, wmOperator *op)
         bke::AnonymousAttributePropagationInfo propagation_info;
         propagation_info.propagate_all = false;
         Mesh *mesh = bke::curve_to_wire_mesh(curves_eval->geometry.wrap(), propagation_info);
+        if (!mesh) {
+          mesh = BKE_mesh_new_nomain(0, 0, 0, 0);
+        }
         BKE_mesh_nomain_to_mesh(mesh, new_mesh, newob);
         BKE_object_material_from_eval_data(bmain, newob, &curves_eval->id);
       }
@@ -3403,9 +3409,6 @@ static int object_convert_exec(bContext *C, wmOperator *op)
                     ob->id.name + 2);
       }
 
-      newob->data = new_mesh;
-      newob->type = OB_MESH;
-
       BKE_object_free_derived_caches(newob);
       BKE_object_free_modifiers(newob, 0);
     }
diff --git a/source/blender/editors/object/object_edit.cc b/source/blender/editors/object/object_edit.cc
index 00fd6139503..9bc7b3a3320 100644
--- a/source/blender/editors/object/object_edit.cc
+++ b/source/blender/editors/object/object_edit.cc
@@ -73,7 +73,7 @@
 #include "ED_anim_api.h"
 #include "ED_armature.h"
 #include "ED_curve.h"
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_image.h"
 #include "ED_keyframes_keylist.h"
 #include "ED_lattice.h"
diff --git a/source/blender/editors/object/object_modes.cc b/source/blender/editors/object/object_modes.cc
index 23d17e08455..36ff752e60d 100644
--- a/source/blender/editors/object/object_modes.cc
+++ b/source/blender/editors/object/object_modes.cc
@@ -41,7 +41,7 @@
 #include "DEG_depsgraph_query.h"
 
 #include "ED_armature.h"
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_screen.h"
 #include "ED_transform_snap_object_context.h"
 #include "ED_undo.h"
diff --git a/source/blender/editors/object/object_ops.c b/source/blender/editors/object/object_ops.c
index 51136680e21..2e454c12d96 100644
--- a/source/blender/editors/object/object_ops.c
+++ b/source/blender/editors/object/object_ops.c
@@ -21,7 +21,7 @@
 
 #include "object_intern.h"
 
-#include "MOD_gpencil_lineart.h"
+#include "MOD_gpencil_legacy_lineart.h"
 
 /* ************************** registration **********************************/
 
diff --git a/source/blender/editors/object/object_relations.c b/source/blender/editors/object/object_relations.c
index 252eddb824d..12f119f68ef 100644
--- a/source/blender/editors/object/object_relations.c
+++ b/source/blender/editors/object/object_relations.c
@@ -92,7 +92,7 @@
 
 #include "ED_armature.h"
 #include "ED_curve.h"
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_keyframing.h"
 #include "ED_mesh.h"
 #include "ED_object.h"
diff --git a/source/blender/editors/object/object_transform.cc b/source/blender/editors/object/object_transform.cc
index f693e4918e5..e006afc430a 100644
--- a/source/blender/editors/object/object_transform.cc
+++ b/source/blender/editors/object/object_transform.cc
@@ -61,7 +61,7 @@
 #include "WM_types.h"
 
 #include "ED_armature.h"
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_keyframing.h"
 #include "ED_mesh.h"
 #include "ED_object.h"
diff --git a/source/blender/editors/render/render_opengl.cc b/source/blender/editors/render/render_opengl.cc
index 1dcbfd26535..076d2cc48b1 100644
--- a/source/blender/editors/render/render_opengl.cc
+++ b/source/blender/editors/render/render_opengl.cc
@@ -51,7 +51,7 @@
 #include "WM_api.h"
 #include "WM_types.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_screen.h"
 #include "ED_view3d.h"
 #include "ED_view3d_offscreen.h"
diff --git a/source/blender/editors/render/render_shading.cc b/source/blender/editors/render/render_shading.cc
index 452b6228e50..d26fceb9814 100644
--- a/source/blender/editors/render/render_shading.cc
+++ b/source/blender/editors/render/render_shading.cc
@@ -1829,7 +1829,7 @@ void SCENE_OT_freestyle_lineset_copy(wmOperatorType *ot)
   /* identifiers */
   ot->name = "Copy Line Set";
   ot->idname = "SCENE_OT_freestyle_lineset_copy";
-  ot->description = "Copy the active line set to a buffer";
+  ot->description = "Copy the active line set to the internal clipboard";
 
   /* api callbacks */
   ot->exec = freestyle_lineset_copy_exec;
@@ -1863,7 +1863,7 @@ void SCENE_OT_freestyle_lineset_paste(wmOperatorType *ot)
   /* identifiers */
   ot->name = "Paste Line Set";
   ot->idname = "SCENE_OT_freestyle_lineset_paste";
-  ot->description = "Paste the buffer content to the active line set";
+  ot->description = "Paste the internal clipboard content to the active line set";
 
   /* api callbacks */
   ot->exec = freestyle_lineset_paste_exec;
diff --git a/source/blender/editors/screen/screen_context.c b/source/blender/editors/screen/screen_context.c
index e2e45a2a662..ba07697c6e3 100644
--- a/source/blender/editors/screen/screen_context.c
+++ b/source/blender/editors/screen/screen_context.c
@@ -41,7 +41,7 @@
 #include "ED_anim_api.h"
 #include "ED_armature.h"
 #include "ED_clip.h"
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 
 #include "SEQ_channels.h"
 #include "SEQ_select.h"
diff --git a/source/blender/editors/sculpt_paint/sculpt_dyntopo.cc b/source/blender/editors/sculpt_paint/sculpt_dyntopo.cc
index 80377fd2542..3abee75218f 100644
--- a/source/blender/editors/sculpt_paint/sculpt_dyntopo.cc
+++ b/source/blender/editors/sculpt_paint/sculpt_dyntopo.cc
@@ -161,7 +161,10 @@ static void SCULPT_dynamic_topology_disable_ex(
     CustomData_copy(&geometry->edata, &me->edata, CD_MASK_MESH.emask, geometry->totedge);
     CustomData_copy(&geometry->ldata, &me->ldata, CD_MASK_MESH.lmask, geometry->totloop);
     CustomData_copy(&geometry->pdata, &me->pdata, CD_MASK_MESH.pmask, geometry->totpoly);
-    me->poly_offset_indices = static_cast<int *>(MEM_dupallocN(geometry->poly_offset_indices));
+    blender::implicit_sharing::copy_shared_pointer(geometry->poly_offset_indices,
+                                                   geometry->poly_offsets_sharing_info,
+                                                   &me->poly_offset_indices,
+                                                   &me->runtime->poly_offsets_sharing_info);
   }
   else {
     BKE_sculptsession_bm_to_me(ob, true);
diff --git a/source/blender/editors/sculpt_paint/sculpt_intern.hh b/source/blender/editors/sculpt_paint/sculpt_intern.hh
index a61fb5c1a59..b86ae773630 100644
--- a/source/blender/editors/sculpt_paint/sculpt_intern.hh
+++ b/source/blender/editors/sculpt_paint/sculpt_intern.hh
@@ -16,6 +16,8 @@
 
 #include "BKE_paint.h"
 #include "BKE_pbvh.h"
+
+#include "BLI_implicit_sharing.hh"
 #include "BLI_bitmap.h"
 #include "BLI_compiler_attrs.h"
 #include "BLI_compiler_compat.h"
@@ -147,6 +149,7 @@ struct SculptUndoNodeGeometry {
   CustomData ldata;
   CustomData pdata;
   int *poly_offset_indices;
+  blender::ImplicitSharingInfo *poly_offsets_sharing_info;
   int totvert;
   int totedge;
   int totloop;
diff --git a/source/blender/editors/sculpt_paint/sculpt_undo.cc b/source/blender/editors/sculpt_paint/sculpt_undo.cc
index d4784c24f3a..f99f04db661 100644
--- a/source/blender/editors/sculpt_paint/sculpt_undo.cc
+++ b/source/blender/editors/sculpt_paint/sculpt_undo.cc
@@ -749,7 +749,10 @@ static void sculpt_undo_geometry_store_data(SculptUndoNodeGeometry *geometry, Ob
   CustomData_copy(&mesh->edata, &geometry->edata, CD_MASK_MESH.emask, mesh->totedge);
   CustomData_copy(&mesh->ldata, &geometry->ldata, CD_MASK_MESH.lmask, mesh->totloop);
   CustomData_copy(&mesh->pdata, &geometry->pdata, CD_MASK_MESH.pmask, mesh->totpoly);
-  geometry->poly_offset_indices = static_cast<int *>(MEM_dupallocN(mesh->poly_offset_indices));
+  blender::implicit_sharing::copy_shared_pointer(mesh->poly_offset_indices,
+                                                 mesh->runtime->poly_offsets_sharing_info,
+                                                 &geometry->poly_offset_indices,
+                                                 &geometry->poly_offsets_sharing_info);
 
   geometry->totvert = mesh->totvert;
   geometry->totedge = mesh->totedge;
@@ -775,7 +778,10 @@ static void sculpt_undo_geometry_restore_data(SculptUndoNodeGeometry *geometry,
   CustomData_copy(&geometry->edata, &mesh->edata, CD_MASK_MESH.emask, geometry->totedge);
   CustomData_copy(&geometry->ldata, &mesh->ldata, CD_MASK_MESH.lmask, geometry->totloop);
   CustomData_copy(&geometry->pdata, &mesh->pdata, CD_MASK_MESH.pmask, geometry->totpoly);
-  mesh->poly_offset_indices = static_cast<int *>(MEM_dupallocN(geometry->poly_offset_indices));
+  blender::implicit_sharing::copy_shared_pointer(geometry->poly_offset_indices,
+                                                 geometry->poly_offsets_sharing_info,
+                                                 &mesh->poly_offset_indices,
+                                                 &mesh->runtime->poly_offsets_sharing_info);
 }
 
 static void sculpt_undo_geometry_free_data(SculptUndoNodeGeometry *geometry)
@@ -792,7 +798,8 @@ static void sculpt_undo_geometry_free_data(SculptUndoNodeGeometry *geometry)
   if (geometry->totpoly) {
     CustomData_free(&geometry->pdata, geometry->totpoly);
   }
-  MEM_SAFE_FREE(geometry->poly_offset_indices);
+  blender::implicit_sharing::free_shared_data(&geometry->poly_offset_indices,
+                                              &geometry->poly_offsets_sharing_info);
 }
 
 static void sculpt_undo_geometry_restore(SculptUndoNode *unode, Object *object)
diff --git a/source/blender/editors/space_action/action_data.cc b/source/blender/editors/space_action/action_data.cc
index e7dcaa9559f..f59944bb62a 100644
--- a/source/blender/editors/space_action/action_data.cc
+++ b/source/blender/editors/space_action/action_data.cc
@@ -38,7 +38,7 @@
 #include "UI_view2d.h"
 
 #include "ED_anim_api.h"
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_keyframes_edit.h"
 #include "ED_keyframing.h"
 #include "ED_markers.h"
diff --git a/source/blender/editors/space_action/action_edit.cc b/source/blender/editors/space_action/action_edit.cc
index d805f3cce5e..ddaaf217b1f 100644
--- a/source/blender/editors/space_action/action_edit.cc
+++ b/source/blender/editors/space_action/action_edit.cc
@@ -40,7 +40,7 @@
 #include "UI_view2d.h"
 
 #include "ED_anim_api.h"
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_keyframes_edit.h"
 #include "ED_keyframing.h"
 #include "ED_markers.h"
@@ -576,7 +576,7 @@ static int actkeys_copy_exec(bContext *C, wmOperator *op)
   if (ac.datatype == ANIMCONT_GPENCIL) {
     if (ED_gpencil_anim_copybuf_copy(&ac) == false) {
       /* check if anything ended up in the buffer */
-      BKE_report(op->reports, RPT_ERROR, "No keyframes copied to keyframes copy/paste buffer");
+      BKE_report(op->reports, RPT_ERROR, "No keyframes copied to the internal clipboard");
       return OPERATOR_CANCELLED;
     }
   }
@@ -591,7 +591,7 @@ static int actkeys_copy_exec(bContext *C, wmOperator *op)
     const bool gpf_ok = ED_gpencil_anim_copybuf_copy(&ac);
 
     if (kf_empty && !gpf_ok) {
-      BKE_report(op->reports, RPT_ERROR, "No keyframes copied to keyframes copy/paste buffer");
+      BKE_report(op->reports, RPT_ERROR, "No keyframes copied to the internal clipboard");
       return OPERATOR_CANCELLED;
     }
   }
@@ -604,7 +604,7 @@ void ACTION_OT_copy(wmOperatorType *ot)
   /* identifiers */
   ot->name = "Copy Keyframes";
   ot->idname = "ACTION_OT_copy";
-  ot->description = "Copy selected keyframes to the copy/paste buffer";
+  ot->description = "Copy selected keyframes to the internal clipboard";
 
   /* api callbacks */
   ot->exec = actkeys_copy_exec;
@@ -635,7 +635,7 @@ static int actkeys_paste_exec(bContext *C, wmOperator *op)
   /* paste keyframes */
   if (ac.datatype == ANIMCONT_GPENCIL) {
     if (ED_gpencil_anim_copybuf_paste(&ac, offset_mode) == false) {
-      BKE_report(op->reports, RPT_ERROR, "No data in buffer to paste");
+      BKE_report(op->reports, RPT_ERROR, "No data in the internal clipboard to paste");
       return OPERATOR_CANCELLED;
     }
   }
@@ -664,7 +664,7 @@ static int actkeys_paste_exec(bContext *C, wmOperator *op)
           return OPERATOR_CANCELLED;
 
         case KEYFRAME_PASTE_NOTHING_TO_PASTE:
-          BKE_report(op->reports, RPT_ERROR, "No data in buffer to paste");
+          BKE_report(op->reports, RPT_ERROR, "No data in the internal clipboard to paste");
           return OPERATOR_CANCELLED;
       }
     }
@@ -698,7 +698,8 @@ void ACTION_OT_paste(wmOperatorType *ot)
   ot->name = "Paste Keyframes";
   ot->idname = "ACTION_OT_paste";
   ot->description =
-      "Paste keyframes from copy/paste buffer for the selected channels, starting on the current "
+      "Paste keyframes from the internal clipboard for the selected channels, starting on the "
+      "current "
       "frame";
 
   /* api callbacks */
diff --git a/source/blender/editors/space_action/action_select.cc b/source/blender/editors/space_action/action_select.cc
index bc9fb3ca7f4..abed2e4aa43 100644
--- a/source/blender/editors/space_action/action_select.cc
+++ b/source/blender/editors/space_action/action_select.cc
@@ -35,7 +35,7 @@
 #include "UI_view2d.h"
 
 #include "ED_anim_api.h"
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_keyframes_edit.h"
 #include "ED_keyframes_keylist.h"
 #include "ED_markers.h"
diff --git a/source/blender/editors/space_api/spacetypes.c b/source/blender/editors/space_api/spacetypes.c
index 0ed48924bbe..56aa0104329 100644
--- a/source/blender/editors/space_api/spacetypes.c
+++ b/source/blender/editors/space_api/spacetypes.c
@@ -33,7 +33,7 @@
 #include "ED_fileselect.h"
 #include "ED_geometry.h"
 #include "ED_gizmo_library.h"
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_lattice.h"
 #include "ED_markers.h"
 #include "ED_mask.h"
diff --git a/source/blender/editors/space_clip/clip_draw.cc b/source/blender/editors/space_clip/clip_draw.cc
index e5beccd2b75..a321dc1bebd 100644
--- a/source/blender/editors/space_clip/clip_draw.cc
+++ b/source/blender/editors/space_clip/clip_draw.cc
@@ -27,7 +27,7 @@
 #include "BKE_tracking.h"
 
 #include "ED_clip.h"
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_mask.h"
 #include "ED_screen.h"
 #include "ED_util.h"
diff --git a/source/blender/editors/space_clip/tracking_ops.cc b/source/blender/editors/space_clip/tracking_ops.cc
index ae59cf672a1..48782a51145 100644
--- a/source/blender/editors/space_clip/tracking_ops.cc
+++ b/source/blender/editors/space_clip/tracking_ops.cc
@@ -1874,7 +1874,7 @@ void CLIP_OT_copy_tracks(wmOperatorType *ot)
 {
   /* identifiers */
   ot->name = "Copy Tracks";
-  ot->description = "Copy selected tracks to clipboard";
+  ot->description = "Copy the selected tracks to the internal clipboard";
   ot->idname = "CLIP_OT_copy_tracks";
 
   /* api callbacks */
@@ -1919,7 +1919,7 @@ void CLIP_OT_paste_tracks(wmOperatorType *ot)
 {
   /* identifiers */
   ot->name = "Paste Tracks";
-  ot->description = "Paste tracks from clipboard";
+  ot->description = "Paste tracks from the internal clipboard";
   ot->idname = "CLIP_OT_paste_tracks";
 
   /* api callbacks */
diff --git a/source/blender/editors/space_graph/graph_edit.c b/source/blender/editors/space_graph/graph_edit.c
index 0efc653c81b..941e211c3ad 100644
--- a/source/blender/editors/space_graph/graph_edit.c
+++ b/source/blender/editors/space_graph/graph_edit.c
@@ -523,7 +523,7 @@ static int graphkeys_copy_exec(bContext *C, wmOperator *op)
 
   /* Copy keyframes. */
   if (copy_graph_keys(&ac)) {
-    BKE_report(op->reports, RPT_ERROR, "No keyframes copied to keyframes copy/paste buffer");
+    BKE_report(op->reports, RPT_ERROR, "No keyframes copied to the internal clipboard");
     return OPERATOR_CANCELLED;
   }
 
@@ -536,7 +536,7 @@ void GRAPH_OT_copy(wmOperatorType *ot)
   /* Identifiers */
   ot->name = "Copy Keyframes";
   ot->idname = "GRAPH_OT_copy";
-  ot->description = "Copy selected keyframes to the copy/paste buffer";
+  ot->description = "Copy selected keyframes to the internal clipboard";
 
   /* API callbacks */
   ot->exec = graphkeys_copy_exec;
@@ -574,7 +574,7 @@ static int graphkeys_paste_exec(bContext *C, wmOperator *op)
       return OPERATOR_CANCELLED;
 
     case KEYFRAME_PASTE_NOTHING_TO_PASTE:
-      BKE_report(op->reports, RPT_ERROR, "No data in buffer to paste");
+      BKE_report(op->reports, RPT_ERROR, "No data in the internal clipboard to paste");
       return OPERATOR_CANCELLED;
   }
 
@@ -605,7 +605,8 @@ void GRAPH_OT_paste(wmOperatorType *ot)
   ot->name = "Paste Keyframes";
   ot->idname = "GRAPH_OT_paste";
   ot->description =
-      "Paste keyframes from copy/paste buffer for the selected channels, starting on the current "
+      "Paste keyframes from the internal clipboard for the selected channels, starting on the "
+      "current "
       "frame";
 
   /* API callbacks */
diff --git a/source/blender/editors/space_image/image_buttons.c b/source/blender/editors/space_image/image_buttons.c
index 786fcd4075a..db795b254e1 100644
--- a/source/blender/editors/space_image/image_buttons.c
+++ b/source/blender/editors/space_image/image_buttons.c
@@ -31,7 +31,7 @@
 #include "IMB_imbuf.h"
 #include "IMB_imbuf_types.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_image.h"
 #include "ED_screen.h"
 
diff --git a/source/blender/editors/space_image/image_draw.c b/source/blender/editors/space_image/image_draw.c
index 6460e6ebd7b..1693ab74e5b 100644
--- a/source/blender/editors/space_image/image_draw.c
+++ b/source/blender/editors/space_image/image_draw.c
@@ -48,7 +48,7 @@
 
 #include "BLF_api.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_image.h"
 #include "ED_mask.h"
 #include "ED_render.h"
diff --git a/source/blender/editors/space_node/clipboard.cc b/source/blender/editors/space_node/clipboard.cc
index df11489f757..a0bab859025 100644
--- a/source/blender/editors/space_node/clipboard.cc
+++ b/source/blender/editors/space_node/clipboard.cc
@@ -167,7 +167,7 @@ static int node_clipboard_copy_exec(bContext *C, wmOperator * /*op*/)
 void NODE_OT_clipboard_copy(wmOperatorType *ot)
 {
   ot->name = "Copy to Clipboard";
-  ot->description = "Copies selected nodes to the clipboard";
+  ot->description = "Copy the selected nodes to the internal clipboard";
   ot->idname = "NODE_OT_clipboard_copy";
 
   ot->exec = node_clipboard_copy_exec;
@@ -191,7 +191,7 @@ static int node_clipboard_paste_exec(bContext *C, wmOperator *op)
   const bool is_valid = clipboard.validate();
 
   if (clipboard.nodes.is_empty()) {
-    BKE_report(op->reports, RPT_ERROR, "Clipboard is empty");
+    BKE_report(op->reports, RPT_ERROR, "The internal clipboard is empty");
     return OPERATOR_CANCELLED;
   }
 
@@ -311,7 +311,7 @@ static int node_clipboard_paste_invoke(bContext *C, wmOperator *op, const wmEven
 void NODE_OT_clipboard_paste(wmOperatorType *ot)
 {
   ot->name = "Paste from Clipboard";
-  ot->description = "Pastes nodes from the clipboard to the active node tree";
+  ot->description = "Paste nodes from the internal clipboard to the active node tree";
   ot->idname = "NODE_OT_clipboard_paste";
 
   ot->invoke = node_clipboard_paste_invoke;
diff --git a/source/blender/editors/space_node/node_draw.cc b/source/blender/editors/space_node/node_draw.cc
index 3192db22e07..560a07dee3b 100644
--- a/source/blender/editors/space_node/node_draw.cc
+++ b/source/blender/editors/space_node/node_draw.cc
@@ -58,7 +58,7 @@
 #include "WM_api.h"
 #include "WM_types.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_node.h"
 #include "ED_node.hh"
 #include "ED_screen.h"
diff --git a/source/blender/editors/space_node/node_geometry_attribute_search.cc b/source/blender/editors/space_node/node_geometry_attribute_search.cc
index 982ea27374f..01f08e1f969 100644
--- a/source/blender/editors/space_node/node_geometry_attribute_search.cc
+++ b/source/blender/editors/space_node/node_geometry_attribute_search.cc
@@ -144,6 +144,7 @@ static eCustomDataType data_type_in_attribute_input_node(const eCustomDataType t
       /* Unsupported currently. */
       return CD_PROP_FLOAT;
     case CD_PROP_FLOAT2:
+    case CD_PROP_INT32_2D:
       /* No 2D vector sockets currently. */
       return CD_PROP_FLOAT3;
     case CD_PROP_INT8:
diff --git a/source/blender/editors/space_outliner/outliner_edit.cc b/source/blender/editors/space_outliner/outliner_edit.cc
index 62f851d4c6e..4ea83f4720c 100644
--- a/source/blender/editors/space_outliner/outliner_edit.cc
+++ b/source/blender/editors/space_outliner/outliner_edit.cc
@@ -822,7 +822,7 @@ void OUTLINER_OT_id_copy(wmOperatorType *ot)
   /* identifiers */
   ot->name = "Outliner ID Data Copy";
   ot->idname = "OUTLINER_OT_id_copy";
-  ot->description = "Selected data-blocks are copied to the clipboard";
+  ot->description = "Copy the selected data-blocks to the internal clipboard";
 
   /* callbacks */
   ot->exec = outliner_id_copy_exec;
@@ -863,7 +863,7 @@ void OUTLINER_OT_id_paste(wmOperatorType *ot)
   /* identifiers */
   ot->name = "Outliner ID Data Paste";
   ot->idname = "OUTLINER_OT_id_paste";
-  ot->description = "Data-blocks from the clipboard are pasted";
+  ot->description = "Paste data-blocks from the internal clipboard";
 
   /* callbacks */
   ot->exec = outliner_id_paste_exec;
diff --git a/source/blender/editors/space_outliner/space_outliner.cc b/source/blender/editors/space_outliner/space_outliner.cc
index b7a3d0d7e64..4406dd7afaf 100644
--- a/source/blender/editors/space_outliner/space_outliner.cc
+++ b/source/blender/editors/space_outliner/space_outliner.cc
@@ -488,7 +488,9 @@ static void outliner_blend_read_lib(BlendLibReader *reader, ID * /*parent_id*/,
 
     BLI_mempool_iternew(space_outliner->treestore, &iter);
     while ((tselem = static_cast<TreeStoreElem *>(BLI_mempool_iterstep(&iter)))) {
-      BLO_read_id_address(reader, nullptr, &tselem->id);
+      if (TSE_IS_REAL_ID(tselem)) {
+        BLO_read_id_address(reader, nullptr, &tselem->id);
+      }
     }
     /* rebuild hash table, because it depends on ids too */
     space_outliner->storeflag |= SO_TREESTORE_REBUILD;
diff --git a/source/blender/editors/space_sequencer/sequencer_draw.c b/source/blender/editors/space_sequencer/sequencer_draw.c
index debdb677d63..b257eb401c1 100644
--- a/source/blender/editors/space_sequencer/sequencer_draw.c
+++ b/source/blender/editors/space_sequencer/sequencer_draw.c
@@ -43,7 +43,7 @@
 #include "GPU_viewport.h"
 
 #include "ED_anim_api.h"
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_markers.h"
 #include "ED_mask.h"
 #include "ED_screen.h"
diff --git a/source/blender/editors/space_sequencer/sequencer_edit.c b/source/blender/editors/space_sequencer/sequencer_edit.c
index f6a9ae8dc60..ba5e770f81c 100644
--- a/source/blender/editors/space_sequencer/sequencer_edit.c
+++ b/source/blender/editors/space_sequencer/sequencer_edit.c
@@ -2483,7 +2483,7 @@ void SEQUENCER_OT_copy(wmOperatorType *ot)
   /* Identifiers. */
   ot->name = "Copy";
   ot->idname = "SEQUENCER_OT_copy";
-  ot->description = "Copy selected strips to clipboard";
+  ot->description = "Copy the selected strips to the internal clipboard";
 
   /* Api callbacks. */
   ot->exec = sequencer_copy_exec;
@@ -2630,7 +2630,7 @@ void SEQUENCER_OT_paste(wmOperatorType *ot)
   /* Identifiers. */
   ot->name = "Paste";
   ot->idname = "SEQUENCER_OT_paste";
-  ot->description = "Paste strips from clipboard";
+  ot->description = "Paste strips from the internal clipboard";
 
   /* Api callbacks. */
   ot->exec = sequencer_paste_exec;
diff --git a/source/blender/editors/space_spreadsheet/space_spreadsheet.cc b/source/blender/editors/space_spreadsheet/space_spreadsheet.cc
index 52c1fa7a3ec..3c4bb00730f 100644
--- a/source/blender/editors/space_spreadsheet/space_spreadsheet.cc
+++ b/source/blender/editors/space_spreadsheet/space_spreadsheet.cc
@@ -335,6 +335,7 @@ static float get_default_column_width(const ColumnValues &values)
       return float_width;
     case SPREADSHEET_VALUE_TYPE_FLOAT:
       return float_width;
+    case SPREADSHEET_VALUE_TYPE_INT32_2D:
     case SPREADSHEET_VALUE_TYPE_FLOAT2:
       return 2.0f * float_width;
     case SPREADSHEET_VALUE_TYPE_FLOAT3:
diff --git a/source/blender/editors/space_spreadsheet/spreadsheet_column.cc b/source/blender/editors/space_spreadsheet/spreadsheet_column.cc
index 078fa3c1c02..d0327cfc990 100644
--- a/source/blender/editors/space_spreadsheet/spreadsheet_column.cc
+++ b/source/blender/editors/space_spreadsheet/spreadsheet_column.cc
@@ -30,6 +30,9 @@ eSpreadsheetColumnValueType cpp_type_to_column_type(const CPPType &type)
   if (type.is<int>()) {
     return SPREADSHEET_VALUE_TYPE_INT32;
   }
+  if (type.is<int2>()) {
+    return SPREADSHEET_VALUE_TYPE_INT32_2D;
+  }
   if (type.is<float>()) {
     return SPREADSHEET_VALUE_TYPE_FLOAT;
   }
diff --git a/source/blender/editors/space_spreadsheet/spreadsheet_layout.cc b/source/blender/editors/space_spreadsheet/spreadsheet_layout.cc
index 2f5ff624540..cd9fb6f5167 100644
--- a/source/blender/editors/space_spreadsheet/spreadsheet_layout.cc
+++ b/source/blender/editors/space_spreadsheet/spreadsheet_layout.cc
@@ -138,6 +138,10 @@ class SpreadsheetLayoutDrawer : public SpreadsheetDrawer {
       UI_but_drawflag_disable(but, UI_BUT_TEXT_LEFT);
       UI_but_drawflag_enable(but, UI_BUT_TEXT_RIGHT);
     }
+    else if (data.type().is<int2>()) {
+      const int2 value = data.get<int2>(real_index);
+      this->draw_int_vector(params, Span(&value.x, 2));
+    }
     else if (data.type().is<float>()) {
       const float value = data.get<float>(real_index);
       std::stringstream ss;
@@ -311,6 +315,36 @@ class SpreadsheetLayoutDrawer : public SpreadsheetDrawer {
     }
   }
 
+  void draw_int_vector(const CellDrawParams &params, const Span<int> values) const
+  {
+    BLI_assert(!values.is_empty());
+    const float segment_width = float(params.width) / values.size();
+    for (const int i : values.index_range()) {
+      std::stringstream ss;
+      const int value = values[i];
+      ss << " " << value;
+      const std::string value_str = ss.str();
+      uiBut *but = uiDefIconTextBut(params.block,
+                                    UI_BTYPE_LABEL,
+                                    0,
+                                    ICON_NONE,
+                                    value_str.c_str(),
+                                    params.xmin + i * segment_width,
+                                    params.ymin,
+                                    segment_width,
+                                    params.height,
+                                    nullptr,
+                                    0,
+                                    0,
+                                    0,
+                                    0,
+                                    nullptr);
+      /* Right-align Floats. */
+      UI_but_drawflag_disable(but, UI_BUT_TEXT_LEFT);
+      UI_but_drawflag_enable(but, UI_BUT_TEXT_RIGHT);
+    }
+  }
+
   void draw_byte_color(const CellDrawParams &params, const ColorGeometry4b color) const
   {
     const ColorGeometry4f float_color = color.decode();
diff --git a/source/blender/editors/space_spreadsheet/spreadsheet_row_filter.cc b/source/blender/editors/space_spreadsheet/spreadsheet_row_filter.cc
index 303d3f1a688..79b58c07fe8 100644
--- a/source/blender/editors/space_spreadsheet/spreadsheet_row_filter.cc
+++ b/source/blender/editors/space_spreadsheet/spreadsheet_row_filter.cc
@@ -140,6 +140,36 @@ static void apply_row_filter(const SpreadsheetRowFilter &row_filter,
       }
     }
   }
+  else if (column_data.type().is<int2>()) {
+    const int2 value = row_filter.value_int2;
+    switch (row_filter.operation) {
+      case SPREADSHEET_ROW_FILTER_EQUAL: {
+        const float threshold_sq = pow2f(row_filter.threshold);
+        apply_filter_operation(
+            column_data.typed<int2>(),
+            [&](const int2 cell) { return math::distance_squared(cell, value) <= threshold_sq; },
+            prev_mask,
+            new_indices);
+        break;
+      }
+      case SPREADSHEET_ROW_FILTER_GREATER: {
+        apply_filter_operation(
+            column_data.typed<int2>(),
+            [&](const int2 cell) { return cell.x > value.x && cell.y > value.y; },
+            prev_mask,
+            new_indices);
+        break;
+      }
+      case SPREADSHEET_ROW_FILTER_LESS: {
+        apply_filter_operation(
+            column_data.typed<int2>(),
+            [&](const int2 cell) { return cell.x < value.x && cell.y < value.y; },
+            prev_mask,
+            new_indices);
+        break;
+      }
+    }
+  }
   else if (column_data.type().is<float2>()) {
     const float2 value = row_filter.value_float2;
     switch (row_filter.operation) {
diff --git a/source/blender/editors/space_spreadsheet/spreadsheet_row_filter_ui.cc b/source/blender/editors/space_spreadsheet/spreadsheet_row_filter_ui.cc
index fa22da4f26a..5007e859a0f 100644
--- a/source/blender/editors/space_spreadsheet/spreadsheet_row_filter_ui.cc
+++ b/source/blender/editors/space_spreadsheet/spreadsheet_row_filter_ui.cc
@@ -68,6 +68,11 @@ static std::string value_string(const SpreadsheetRowFilter &row_filter,
       result << std::fixed << row_filter.value_float;
       return result.str();
     }
+    case SPREADSHEET_VALUE_TYPE_INT32_2D: {
+      std::ostringstream result;
+      result << "(" << row_filter.value_int2[0] << ", " << row_filter.value_int2[1] << ")";
+      return result.str();
+    }
     case SPREADSHEET_VALUE_TYPE_FLOAT2: {
       std::ostringstream result;
       result.precision(3);
@@ -198,6 +203,10 @@ static void spreadsheet_filter_panel_draw(const bContext *C, Panel *panel)
       uiItemR(layout, filter_ptr, "operation", 0, nullptr, ICON_NONE);
       uiItemR(layout, filter_ptr, "value_int", 0, IFACE_("Value"), ICON_NONE);
       break;
+    case SPREADSHEET_VALUE_TYPE_INT32_2D:
+      uiItemR(layout, filter_ptr, "operation", 0, nullptr, ICON_NONE);
+      uiItemR(layout, filter_ptr, "value_int2", 0, IFACE_("Value"), ICON_NONE);
+      break;
     case SPREADSHEET_VALUE_TYPE_FLOAT:
       uiItemR(layout, filter_ptr, "operation", 0, nullptr, ICON_NONE);
       uiItemR(layout, filter_ptr, "value_float", 0, IFACE_("Value"), ICON_NONE);
diff --git a/source/blender/editors/space_view3d/view3d_draw.cc b/source/blender/editors/space_view3d/view3d_draw.cc
index 9755599e989..86a7033d0df 100644
--- a/source/blender/editors/space_view3d/view3d_draw.cc
+++ b/source/blender/editors/space_view3d/view3d_draw.cc
@@ -48,7 +48,7 @@
 #include "DRW_engine.h"
 #include "DRW_select_buffer.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_info.h"
 #include "ED_keyframing.h"
 #include "ED_screen.h"
diff --git a/source/blender/editors/space_view3d/view3d_gizmo_ruler.c b/source/blender/editors/space_view3d/view3d_gizmo_ruler.c
index fd940470cc1..16195a896bd 100644
--- a/source/blender/editors/space_view3d/view3d_gizmo_ruler.c
+++ b/source/blender/editors/space_view3d/view3d_gizmo_ruler.c
@@ -30,7 +30,7 @@
 
 #include "ED_gizmo_library.h"
 #include "ED_gizmo_utils.h"
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_screen.h"
 #include "ED_transform.h"
 #include "ED_transform_snap_object_context.h"
diff --git a/source/blender/editors/space_view3d/view3d_ops.c b/source/blender/editors/space_view3d/view3d_ops.c
index 0274ff603c6..c808d810680 100644
--- a/source/blender/editors/space_view3d/view3d_ops.c
+++ b/source/blender/editors/space_view3d/view3d_ops.c
@@ -72,7 +72,7 @@ static void VIEW3D_OT_copybuffer(wmOperatorType *ot)
   /* identifiers */
   ot->name = "Copy Objects";
   ot->idname = "VIEW3D_OT_copybuffer";
-  ot->description = "Selected objects are copied to the clipboard";
+  ot->description = "Copy the selected objects to the internal clipboard";
 
   /* api callbacks */
   ot->exec = view3d_copybuffer_exec;
@@ -113,7 +113,7 @@ static void VIEW3D_OT_pastebuffer(wmOperatorType *ot)
   /* identifiers */
   ot->name = "Paste Objects";
   ot->idname = "VIEW3D_OT_pastebuffer";
-  ot->description = "Objects from the clipboard are pasted";
+  ot->description = "Paste objects from the internal clipboard";
 
   /* api callbacks */
   ot->exec = view3d_pastebuffer_exec;
diff --git a/source/blender/editors/space_view3d/view3d_select.cc b/source/blender/editors/space_view3d/view3d_select.cc
index 50adf47b799..3a9b366f03a 100644
--- a/source/blender/editors/space_view3d/view3d_select.cc
+++ b/source/blender/editors/space_view3d/view3d_select.cc
@@ -71,7 +71,7 @@
 #include "ED_armature.h"
 #include "ED_curve.h"
 #include "ED_curves.h"
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_lattice.h"
 #include "ED_mball.h"
 #include "ED_mesh.h"
@@ -3664,8 +3664,7 @@ static bool do_mesh_box_select(ViewContext *vc,
   }
   if (ts->selectmode & SCE_SELECT_EDGE) {
     /* Does both use_zbuf and non-use_zbuf versions (need screen cos for both) */
-    struct BoxSelectUserData_ForMeshEdge cb_data {
-    };
+    struct BoxSelectUserData_ForMeshEdge cb_data {};
     cb_data.data = &data;
     cb_data.esel = use_zbuf ? esel : nullptr;
     cb_data.backbuf_offset = use_zbuf ? DRW_select_buffer_context_offset_for_object_elem(
diff --git a/source/blender/editors/transform/CMakeLists.txt b/source/blender/editors/transform/CMakeLists.txt
index d75f0c0c8cd..338e91589c6 100644
--- a/source/blender/editors/transform/CMakeLists.txt
+++ b/source/blender/editors/transform/CMakeLists.txt
@@ -31,7 +31,7 @@ set(SRC
   transform_convert_cursor.c
   transform_convert_curve.c
   transform_convert_curves.cc
-  transform_convert_gpencil.c
+  transform_convert_gpencil_legacy.c
   transform_convert_graph.c
   transform_convert_lattice.c
   transform_convert_mask.c
diff --git a/source/blender/editors/transform/transform.c b/source/blender/editors/transform/transform.c
index 78a42f1a3d8..b584eacce0a 100644
--- a/source/blender/editors/transform/transform.c
+++ b/source/blender/editors/transform/transform.c
@@ -26,7 +26,7 @@
 #include "GPU_state.h"
 
 #include "ED_clip.h"
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_image.h"
 #include "ED_keyframing.h"
 #include "ED_node.h"
diff --git a/source/blender/editors/transform/transform_convert.h b/source/blender/editors/transform/transform_convert.h
index bc7c4058d66..c409b2a4f31 100644
--- a/source/blender/editors/transform/transform_convert.h
+++ b/source/blender/editors/transform/transform_convert.h
@@ -142,7 +142,7 @@ extern TransConvertTypeInfo TransConvertType_Curves;
 
 extern TransConvertTypeInfo TransConvertType_Graph;
 
-/* transform_convert_gpencil.c */
+/* transform_convert_gpencil_legacy.c */
 
 extern TransConvertTypeInfo TransConvertType_GPencil;
 
diff --git a/source/blender/editors/transform/transform_convert_gpencil.c b/source/blender/editors/transform/transform_convert_gpencil_legacy.c
similarity index 99%
rename from source/blender/editors/transform/transform_convert_gpencil.c
rename to source/blender/editors/transform/transform_convert_gpencil_legacy.c
index 20e494ecdab..0446b14119b 100644
--- a/source/blender/editors/transform/transform_convert_gpencil.c
+++ b/source/blender/editors/transform/transform_convert_gpencil_legacy.c
@@ -21,7 +21,7 @@
 #include "BKE_gpencil_legacy.h"
 #include "BKE_layer.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_keyframing.h"
 
 #include "transform.h"
diff --git a/source/blender/editors/transform/transform_gizmo_3d.cc b/source/blender/editors/transform/transform_gizmo_3d.cc
index af6db57e275..e61990732ee 100644
--- a/source/blender/editors/transform/transform_gizmo_3d.cc
+++ b/source/blender/editors/transform/transform_gizmo_3d.cc
@@ -34,7 +34,7 @@
 #include "ED_curves.h"
 #include "ED_gizmo_library.h"
 #include "ED_gizmo_utils.h"
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_object.h"
 #include "ED_particle.h"
 #include "ED_screen.h"
diff --git a/source/blender/editors/undo/ed_undo.cc b/source/blender/editors/undo/ed_undo.cc
index d22c97cb9d4..dfd1f4c6860 100644
--- a/source/blender/editors/undo/ed_undo.cc
+++ b/source/blender/editors/undo/ed_undo.cc
@@ -35,7 +35,7 @@
 #include "BLO_blend_validate.h"
 
 #include "ED_asset.h"
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_object.h"
 #include "ED_outliner.h"
 #include "ED_render.h"
diff --git a/source/blender/editors/util/CMakeLists.txt b/source/blender/editors/util/CMakeLists.txt
index 66c3b9da74c..90f81030669 100644
--- a/source/blender/editors/util/CMakeLists.txt
+++ b/source/blender/editors/util/CMakeLists.txt
@@ -52,7 +52,7 @@ set(SRC
   ../include/ED_geometry.h
   ../include/ED_gizmo_library.h
   ../include/ED_gizmo_utils.h
-  ../include/ED_gpencil.h
+  ../include/ED_gpencil_legacy.h
   ../include/ED_image.h
   ../include/ED_info.h
   ../include/ED_keyframes_draw.h
diff --git a/source/blender/editors/util/ed_util.cc b/source/blender/editors/util/ed_util.cc
index 3e19a3f701d..b04ba65edd0 100644
--- a/source/blender/editors/util/ed_util.cc
+++ b/source/blender/editors/util/ed_util.cc
@@ -37,7 +37,7 @@
 
 #include "ED_armature.h"
 #include "ED_asset.h"
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_image.h"
 #include "ED_mesh.h"
 #include "ED_object.h"
diff --git a/source/blender/functions/intern/cpp_types.cc b/source/blender/functions/intern/cpp_types.cc
index e7abe7899a2..e11ed0b56e1 100644
--- a/source/blender/functions/intern/cpp_types.cc
+++ b/source/blender/functions/intern/cpp_types.cc
@@ -17,6 +17,7 @@ FN_FIELD_CPP_TYPE_MAKE(blender::ColorGeometry4b);
 FN_FIELD_CPP_TYPE_MAKE(bool);
 FN_FIELD_CPP_TYPE_MAKE(int8_t);
 FN_FIELD_CPP_TYPE_MAKE(int32_t);
+FN_FIELD_CPP_TYPE_MAKE(blender::int2);
 FN_FIELD_CPP_TYPE_MAKE(std::string);
 
 BLI_VECTOR_CPP_TYPE_MAKE(blender::fn::ValueOrField<std::string>);
@@ -31,6 +32,7 @@ void FN_register_cpp_types()
   FN_FIELD_CPP_TYPE_REGISTER(bool);
   FN_FIELD_CPP_TYPE_REGISTER(int8_t);
   FN_FIELD_CPP_TYPE_REGISTER(int32_t);
+  FN_FIELD_CPP_TYPE_REGISTER(blender::int2);
   FN_FIELD_CPP_TYPE_REGISTER(std::string);
 
   BLI_VECTOR_CPP_TYPE_REGISTER(blender::fn::ValueOrField<std::string>);
diff --git a/source/blender/geometry/intern/mesh_split_edges.cc b/source/blender/geometry/intern/mesh_split_edges.cc
index 784f468ef06..4908c67e288 100644
--- a/source/blender/geometry/intern/mesh_split_edges.cc
+++ b/source/blender/geometry/intern/mesh_split_edges.cc
@@ -28,6 +28,11 @@ static void copy_to_new_verts(MutableSpan<T> data, const Span<int> new_to_old_ve
 
 static void add_new_vertices(Mesh &mesh, const Span<int> new_to_old_verts_map)
 {
+  /* These types aren't supported for interpolation below. */
+  CustomData_free_layers(&mesh.vdata, CD_BWEIGHT, mesh.totvert);
+  CustomData_free_layers(&mesh.vdata, CD_SHAPEKEY, mesh.totvert);
+  CustomData_free_layers(&mesh.vdata, CD_CLOTH_ORCO, mesh.totvert);
+  CustomData_free_layers(&mesh.vdata, CD_MVERT_SKIN, mesh.totvert);
   CustomData_realloc(&mesh.vdata, mesh.totvert, mesh.totvert + new_to_old_verts_map.size());
   mesh.totvert += new_to_old_verts_map.size();
 
diff --git a/source/blender/gpencil_modifiers/CMakeLists.txt b/source/blender/gpencil_modifiers/CMakeLists.txt
deleted file mode 100644
index 91a17a5f00f..00000000000
--- a/source/blender/gpencil_modifiers/CMakeLists.txt
+++ /dev/null
@@ -1,101 +0,0 @@
-# SPDX-License-Identifier: GPL-2.0-or-later
-# Copyright 2018 Blender Foundation
-
-set(INC
-  .
-  intern
-  ../blenfont
-  ../blenkernel
-  ../blenlib
-  ../blentranslation
-  ../bmesh
-  ../depsgraph
-  ../editors/include
-  ../makesdna
-  ../makesrna
-  ../render
-  ../windowmanager
-  ../../../intern/eigen
-  ../../../intern/guardedalloc
-
-  # dna_type_offsets.h in BLO_read_write.h
-  ${CMAKE_BINARY_DIR}/source/blender/makesdna/intern
-  # RNA_prototypes.h
-  ${CMAKE_BINARY_DIR}/source/blender/makesrna
-)
-
-set(INC_SYS
-  ${ZLIB_INCLUDE_DIRS}
-)
-
-set(SRC
-  intern/MOD_gpencil_ui_common.c
-
-  intern/MOD_gpencil_util.c
-  intern/MOD_gpencilarmature.c
-  intern/MOD_gpencilarray.c
-  intern/MOD_gpencilbuild.c
-  intern/MOD_gpencilcolor.c
-  intern/MOD_gpencildash.c
-  intern/MOD_gpencilenvelope.c
-  intern/MOD_gpencilhook.c
-  intern/MOD_gpencillattice.c
-  intern/MOD_gpencillength.c
-  intern/MOD_gpencillineart.c
-  intern/MOD_gpencilmirror.c
-  intern/MOD_gpencilmultiply.c
-  intern/MOD_gpencilnoise.c
-  intern/MOD_gpenciloffset.c
-  intern/MOD_gpencilopacity.c
-  intern/MOD_gpenciloutline.c
-  intern/MOD_gpencilshrinkwrap.c
-  intern/MOD_gpencilsimplify.c
-  intern/MOD_gpencilsmooth.c
-  intern/MOD_gpencilsubdiv.c
-  intern/MOD_gpenciltexture.c
-  intern/MOD_gpencilthick.c
-  intern/MOD_gpenciltime.c
-  intern/MOD_gpenciltint.c
-  intern/MOD_gpencilweight_angle.c
-  intern/MOD_gpencilweight_proximity.c
-
-  MOD_gpencil_lineart.h
-  MOD_gpencil_modifiertypes.h
-  intern/MOD_gpencil_ui_common.h
-  intern/MOD_gpencil_util.h
-
-  # Lineart code
-  intern/lineart/lineart_chain.c
-  intern/lineart/lineart_cpu.cc
-  intern/lineart/lineart_ops.c
-  intern/lineart/lineart_shadow.c
-  intern/lineart/lineart_util.c
-
-  intern/lineart/MOD_lineart.h
-  intern/lineart/lineart_intern.h
-)
-
-if(WITH_TBB)
-add_definitions(-DWITH_TBB)
-if(WIN32)
-  # TBB includes Windows.h which will define min/max macros
-  # that will collide with the stl versions.
-  add_definitions(-DNOMINMAX)
-endif()
-list(APPEND INC_SYS
-  ${TBB_INCLUDE_DIRS}
-)
-
-list(APPEND LIB
-  ${TBB_LIBRARIES}
-)
-endif()
-
-set(LIB
-)
-
-blender_add_lib(bf_gpencil_modifiers "${SRC}" "${INC}" "${INC_SYS}" "${LIB}")
-
-add_dependencies(bf_gpencil_modifiers bf_dna)
-# RNA_prototypes.h
-add_dependencies(bf_gpencil_modifiers bf_rna)
diff --git a/source/blender/gpencil_modifiers_legacy/CMakeLists.txt b/source/blender/gpencil_modifiers_legacy/CMakeLists.txt
new file mode 100644
index 00000000000..5a5dbd4bb1f
--- /dev/null
+++ b/source/blender/gpencil_modifiers_legacy/CMakeLists.txt
@@ -0,0 +1,101 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Copyright 2018 Blender Foundation
+
+set(INC
+  .
+  intern
+  ../blenfont
+  ../blenkernel
+  ../blenlib
+  ../blentranslation
+  ../bmesh
+  ../depsgraph
+  ../editors/include
+  ../makesdna
+  ../makesrna
+  ../render
+  ../windowmanager
+  ../../../intern/eigen
+  ../../../intern/guardedalloc
+
+  # dna_type_offsets.h in BLO_read_write.h
+  ${CMAKE_BINARY_DIR}/source/blender/makesdna/intern
+  # RNA_prototypes.h
+  ${CMAKE_BINARY_DIR}/source/blender/makesrna
+)
+
+set(INC_SYS
+  ${ZLIB_INCLUDE_DIRS}
+)
+
+set(SRC
+  intern/MOD_gpencil_legacy_ui_common.c
+
+  intern/MOD_gpencil_legacy_util.c
+  intern/MOD_gpencil_legacy_armature.c
+  intern/MOD_gpencil_legacy_array.c
+  intern/MOD_gpencil_legacy_build.c
+  intern/MOD_gpencil_legacy_color.c
+  intern/MOD_gpencil_legacy_dash.c
+  intern/MOD_gpencil_legacy_envelope.c
+  intern/MOD_gpencil_legacy_hook.c
+  intern/MOD_gpencil_legacy_lattice.c
+  intern/MOD_gpencil_legacy_length.c
+  intern/MOD_gpencil_legacy_lineart.c
+  intern/MOD_gpencil_legacy_mirror.c
+  intern/MOD_gpencil_legacy_multiply.c
+  intern/MOD_gpencil_legacy_noise.c
+  intern/MOD_gpencil_legacy_offset.c
+  intern/MOD_gpencil_legacy_opacity.c
+  intern/MOD_gpencil_legacy_outline.c
+  intern/MOD_gpencil_legacy_shrinkwrap.c
+  intern/MOD_gpencil_legacy_simplify.c
+  intern/MOD_gpencil_legacy_smooth.c
+  intern/MOD_gpencil_legacy_subdiv.c
+  intern/MOD_gpencil_legacy_texture.c
+  intern/MOD_gpencil_legacy_thick.c
+  intern/MOD_gpencil_legacy_time.c
+  intern/MOD_gpencil_legacy_tint.c
+  intern/MOD_gpencil_legacy_weight_angle.c
+  intern/MOD_gpencil_legacy_weight_proximity.c
+
+  MOD_gpencil_legacy_lineart.h
+  MOD_gpencil_legacy_modifiertypes.h
+  intern/MOD_gpencil_legacy_ui_common.h
+  intern/MOD_gpencil_legacy_util.h
+
+  # Lineart code
+  intern/lineart/lineart_chain.c
+  intern/lineart/lineart_cpu.cc
+  intern/lineart/lineart_ops.c
+  intern/lineart/lineart_shadow.c
+  intern/lineart/lineart_util.c
+
+  intern/lineart/MOD_lineart.h
+  intern/lineart/lineart_intern.h
+)
+
+if(WITH_TBB)
+add_definitions(-DWITH_TBB)
+if(WIN32)
+  # TBB includes Windows.h which will define min/max macros
+  # that will collide with the stl versions.
+  add_definitions(-DNOMINMAX)
+endif()
+list(APPEND INC_SYS
+  ${TBB_INCLUDE_DIRS}
+)
+
+list(APPEND LIB
+  ${TBB_LIBRARIES}
+)
+endif()
+
+set(LIB
+)
+
+blender_add_lib(bf_gpencil_modifiers_legacy "${SRC}" "${INC}" "${INC_SYS}" "${LIB}")
+
+add_dependencies(bf_gpencil_modifiers_legacy bf_dna)
+# RNA_prototypes.h
+add_dependencies(bf_gpencil_modifiers_legacy bf_rna)
diff --git a/source/blender/gpencil_modifiers/MOD_gpencil_lineart.h b/source/blender/gpencil_modifiers_legacy/MOD_gpencil_legacy_lineart.h
similarity index 100%
rename from source/blender/gpencil_modifiers/MOD_gpencil_lineart.h
rename to source/blender/gpencil_modifiers_legacy/MOD_gpencil_legacy_lineart.h
diff --git a/source/blender/gpencil_modifiers/MOD_gpencil_modifiertypes.h b/source/blender/gpencil_modifiers_legacy/MOD_gpencil_legacy_modifiertypes.h
similarity index 98%
rename from source/blender/gpencil_modifiers/MOD_gpencil_modifiertypes.h
rename to source/blender/gpencil_modifiers_legacy/MOD_gpencil_legacy_modifiertypes.h
index 58ccc2299bd..652195ce541 100644
--- a/source/blender/gpencil_modifiers/MOD_gpencil_modifiertypes.h
+++ b/source/blender/gpencil_modifiers_legacy/MOD_gpencil_legacy_modifiertypes.h
@@ -38,6 +38,6 @@ extern GpencilModifierTypeInfo modifierType_Gpencil_Dash;
 extern GpencilModifierTypeInfo modifierType_Gpencil_Shrinkwrap;
 extern GpencilModifierTypeInfo modifierType_Gpencil_Envelope;
 
-/* MOD_gpencil_util.c */
+/* MOD_gpencil_legacy_util.c */
 
 void gpencil_modifier_type_init(GpencilModifierTypeInfo *types[]);
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencilarmature.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_armature.c
similarity index 98%
rename from source/blender/gpencil_modifiers/intern/MOD_gpencilarmature.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_armature.c
index 2b8c0d99b05..15aa95ed01e 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencilarmature.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_armature.c
@@ -39,9 +39,9 @@
 
 #include "RNA_access.h"
 
-#include "MOD_gpencil_modifiertypes.h"
-#include "MOD_gpencil_ui_common.h"
-#include "MOD_gpencil_util.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
+#include "MOD_gpencil_legacy_ui_common.h"
+#include "MOD_gpencil_legacy_util.h"
 
 #include "DEG_depsgraph.h"
 #include "DEG_depsgraph_build.h"
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencilarray.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_array.c
similarity index 99%
rename from source/blender/gpencil_modifiers/intern/MOD_gpencilarray.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_array.c
index 8e949292b11..adedb0458ca 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencilarray.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_array.c
@@ -43,9 +43,9 @@
 #include "DEG_depsgraph_build.h"
 #include "DEG_depsgraph_query.h"
 
-#include "MOD_gpencil_modifiertypes.h"
-#include "MOD_gpencil_ui_common.h"
-#include "MOD_gpencil_util.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
+#include "MOD_gpencil_legacy_ui_common.h"
+#include "MOD_gpencil_legacy_util.h"
 
 typedef struct tmpStrokes {
   struct tmpStrokes *next, *prev;
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencilbuild.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_build.c
similarity index 99%
rename from source/blender/gpencil_modifiers/intern/MOD_gpencilbuild.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_build.c
index 05eb80c0bef..57d743809ee 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencilbuild.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_build.c
@@ -44,8 +44,8 @@
 #include "DEG_depsgraph.h"
 #include "DEG_depsgraph_query.h"
 
-#include "MOD_gpencil_modifiertypes.h"
-#include "MOD_gpencil_ui_common.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
+#include "MOD_gpencil_legacy_ui_common.h"
 
 /* Two hard-coded values for GP_BUILD_MODE_ADDITIVE with GP_BUILD_TIMEMODE_DRAWSPEED. */
 
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencilcolor.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_color.c
similarity index 98%
rename from source/blender/gpencil_modifiers/intern/MOD_gpencilcolor.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_color.c
index da33312d0b5..2ccd6518265 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencilcolor.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_color.c
@@ -36,9 +36,9 @@
 
 #include "DEG_depsgraph.h"
 
-#include "MOD_gpencil_modifiertypes.h"
-#include "MOD_gpencil_ui_common.h"
-#include "MOD_gpencil_util.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
+#include "MOD_gpencil_legacy_ui_common.h"
+#include "MOD_gpencil_legacy_util.h"
 
 static void initData(GpencilModifierData *md)
 {
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencildash.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_dash.c
similarity index 99%
rename from source/blender/gpencil_modifiers/intern/MOD_gpencildash.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_dash.c
index ffbb8d9c1f0..cf8380d30e6 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencildash.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_dash.c
@@ -38,9 +38,9 @@
 
 #include "BLT_translation.h"
 
-#include "MOD_gpencil_modifiertypes.h"
-#include "MOD_gpencil_ui_common.h"
-#include "MOD_gpencil_util.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
+#include "MOD_gpencil_legacy_ui_common.h"
+#include "MOD_gpencil_legacy_util.h"
 
 #include "DEG_depsgraph.h"
 #include "DEG_depsgraph_query.h"
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencilenvelope.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_envelope.c
similarity index 99%
rename from source/blender/gpencil_modifiers/intern/MOD_gpencilenvelope.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_envelope.c
index 5c7400292ed..3ce6ed33648 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencilenvelope.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_envelope.c
@@ -40,9 +40,9 @@
 
 #include "RNA_access.h"
 
-#include "MOD_gpencil_modifiertypes.h"
-#include "MOD_gpencil_ui_common.h"
-#include "MOD_gpencil_util.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
+#include "MOD_gpencil_legacy_ui_common.h"
+#include "MOD_gpencil_legacy_util.h"
 
 #include "MEM_guardedalloc.h"
 
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencilhook.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_hook.c
similarity index 98%
rename from source/blender/gpencil_modifiers/intern/MOD_gpencilhook.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_hook.c
index dc41cc9401f..7aa836c6740 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencilhook.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_hook.c
@@ -42,9 +42,9 @@
 
 #include "RNA_access.h"
 
-#include "MOD_gpencil_modifiertypes.h"
-#include "MOD_gpencil_ui_common.h"
-#include "MOD_gpencil_util.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
+#include "MOD_gpencil_legacy_ui_common.h"
+#include "MOD_gpencil_legacy_util.h"
 
 #include "DEG_depsgraph.h"
 #include "DEG_depsgraph_build.h"
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencillattice.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_lattice.c
similarity index 98%
rename from source/blender/gpencil_modifiers/intern/MOD_gpencillattice.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_lattice.c
index 88a3e8164d0..ccd3ab59e92 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencillattice.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_lattice.c
@@ -37,9 +37,9 @@
 
 #include "RNA_access.h"
 
-#include "MOD_gpencil_modifiertypes.h"
-#include "MOD_gpencil_ui_common.h"
-#include "MOD_gpencil_util.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
+#include "MOD_gpencil_legacy_ui_common.h"
+#include "MOD_gpencil_legacy_util.h"
 
 #include "DEG_depsgraph.h"
 #include "DEG_depsgraph_build.h"
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencillength.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_length.c
similarity index 99%
rename from source/blender/gpencil_modifiers/intern/MOD_gpencillength.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_length.c
index b0a54cb7837..0dca04f568b 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencillength.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_length.c
@@ -38,9 +38,9 @@
 
 #include "RNA_access.h"
 
-#include "MOD_gpencil_modifiertypes.h"
-#include "MOD_gpencil_ui_common.h"
-#include "MOD_gpencil_util.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
+#include "MOD_gpencil_legacy_ui_common.h"
+#include "MOD_gpencil_legacy_util.h"
 
 #include "DEG_depsgraph.h"
 #include "DEG_depsgraph_query.h"
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencillineart.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_lineart.c
similarity index 99%
rename from source/blender/gpencil_modifiers/intern/MOD_gpencillineart.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_lineart.c
index 5546524cccb..9d5074238c9 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencillineart.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_lineart.c
@@ -39,9 +39,9 @@
 #include "DEG_depsgraph.h"
 #include "DEG_depsgraph_query.h"
 
-#include "MOD_gpencil_lineart.h"
-#include "MOD_gpencil_modifiertypes.h"
-#include "MOD_gpencil_ui_common.h"
+#include "MOD_gpencil_legacy_lineart.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
+#include "MOD_gpencil_legacy_ui_common.h"
 #include "lineart/MOD_lineart.h"
 
 static void initData(GpencilModifierData *md)
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencilmirror.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_mirror.c
similarity index 98%
rename from source/blender/gpencil_modifiers/intern/MOD_gpencilmirror.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_mirror.c
index 747dcc239ce..6e3461d6833 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencilmirror.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_mirror.c
@@ -34,9 +34,9 @@
 #include "UI_interface.h"
 #include "UI_resources.h"
 
-#include "MOD_gpencil_modifiertypes.h"
-#include "MOD_gpencil_ui_common.h"
-#include "MOD_gpencil_util.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
+#include "MOD_gpencil_legacy_ui_common.h"
+#include "MOD_gpencil_legacy_util.h"
 
 #include "DEG_depsgraph.h"
 #include "DEG_depsgraph_build.h"
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencilmultiply.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_multiply.c
similarity index 98%
rename from source/blender/gpencil_modifiers/intern/MOD_gpencilmultiply.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_multiply.c
index 6ae2c323c81..bce0f02d6d7 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencilmultiply.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_multiply.c
@@ -40,9 +40,9 @@
 
 #include "RNA_access.h"
 
-#include "MOD_gpencil_modifiertypes.h"
-#include "MOD_gpencil_ui_common.h"
-#include "MOD_gpencil_util.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
+#include "MOD_gpencil_legacy_ui_common.h"
+#include "MOD_gpencil_legacy_util.h"
 
 static void initData(GpencilModifierData *md)
 {
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencilnoise.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_noise.c
similarity index 98%
rename from source/blender/gpencil_modifiers/intern/MOD_gpencilnoise.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_noise.c
index 40394dc09cc..3be6aff0979 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencilnoise.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_noise.c
@@ -41,9 +41,9 @@
 
 #include "RNA_access.h"
 
-#include "MOD_gpencil_modifiertypes.h"
-#include "MOD_gpencil_ui_common.h"
-#include "MOD_gpencil_util.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
+#include "MOD_gpencil_legacy_ui_common.h"
+#include "MOD_gpencil_legacy_util.h"
 
 static void initData(GpencilModifierData *md)
 {
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpenciloffset.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_offset.c
similarity index 98%
rename from source/blender/gpencil_modifiers/intern/MOD_gpenciloffset.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_offset.c
index e787073cda5..e21316f006e 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpenciloffset.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_offset.c
@@ -41,9 +41,9 @@
 #include "UI_interface.h"
 #include "UI_resources.h"
 
-#include "MOD_gpencil_modifiertypes.h"
-#include "MOD_gpencil_ui_common.h"
-#include "MOD_gpencil_util.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
+#include "MOD_gpencil_legacy_ui_common.h"
+#include "MOD_gpencil_legacy_util.h"
 
 static void initData(GpencilModifierData *md)
 {
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencilopacity.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_opacity.c
similarity index 98%
rename from source/blender/gpencil_modifiers/intern/MOD_gpencilopacity.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_opacity.c
index a06c7817f17..9901b4412c8 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencilopacity.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_opacity.c
@@ -35,9 +35,9 @@
 
 #include "RNA_access.h"
 
-#include "MOD_gpencil_modifiertypes.h"
-#include "MOD_gpencil_ui_common.h"
-#include "MOD_gpencil_util.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
+#include "MOD_gpencil_legacy_ui_common.h"
+#include "MOD_gpencil_legacy_util.h"
 
 static void initData(GpencilModifierData *md)
 {
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpenciloutline.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_outline.c
similarity index 98%
rename from source/blender/gpencil_modifiers/intern/MOD_gpenciloutline.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_outline.c
index c71de59bd49..7332d2e0891 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpenciloutline.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_outline.c
@@ -40,9 +40,9 @@
 #include "DEG_depsgraph.h"
 #include "DEG_depsgraph_query.h"
 
-#include "MOD_gpencil_modifiertypes.h"
-#include "MOD_gpencil_ui_common.h"
-#include "MOD_gpencil_util.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
+#include "MOD_gpencil_legacy_ui_common.h"
+#include "MOD_gpencil_legacy_util.h"
 
 static void initData(GpencilModifierData *md)
 {
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencilshrinkwrap.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_shrinkwrap.c
similarity index 98%
rename from source/blender/gpencil_modifiers/intern/MOD_gpencilshrinkwrap.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_shrinkwrap.c
index c4ac6f680e6..2900f51a29e 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencilshrinkwrap.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_shrinkwrap.c
@@ -40,9 +40,9 @@
 
 #include "RNA_access.h"
 
-#include "MOD_gpencil_modifiertypes.h"
-#include "MOD_gpencil_ui_common.h"
-#include "MOD_gpencil_util.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
+#include "MOD_gpencil_legacy_ui_common.h"
+#include "MOD_gpencil_legacy_util.h"
 
 #include "DEG_depsgraph.h"
 #include "DEG_depsgraph_build.h"
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencilsimplify.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_simplify.c
similarity index 97%
rename from source/blender/gpencil_modifiers/intern/MOD_gpencilsimplify.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_simplify.c
index 231da156c84..713c4531043 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencilsimplify.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_simplify.c
@@ -33,9 +33,9 @@
 
 #include "RNA_access.h"
 
-#include "MOD_gpencil_modifiertypes.h"
-#include "MOD_gpencil_ui_common.h"
-#include "MOD_gpencil_util.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
+#include "MOD_gpencil_legacy_ui_common.h"
+#include "MOD_gpencil_legacy_util.h"
 
 static void initData(GpencilModifierData *md)
 {
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencilsmooth.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_smooth.c
similarity index 98%
rename from source/blender/gpencil_modifiers/intern/MOD_gpencilsmooth.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_smooth.c
index 1a60359e7f3..497622ab141 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencilsmooth.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_smooth.c
@@ -36,9 +36,9 @@
 
 #include "RNA_access.h"
 
-#include "MOD_gpencil_modifiertypes.h"
-#include "MOD_gpencil_ui_common.h"
-#include "MOD_gpencil_util.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
+#include "MOD_gpencil_legacy_ui_common.h"
+#include "MOD_gpencil_legacy_util.h"
 
 #include "MEM_guardedalloc.h"
 
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencilsubdiv.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_subdiv.c
similarity index 97%
rename from source/blender/gpencil_modifiers/intern/MOD_gpencilsubdiv.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_subdiv.c
index f68ebebd7d2..bc5ea5a4cf4 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencilsubdiv.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_subdiv.c
@@ -31,9 +31,9 @@
 #include "UI_interface.h"
 #include "UI_resources.h"
 
-#include "MOD_gpencil_modifiertypes.h"
-#include "MOD_gpencil_ui_common.h"
-#include "MOD_gpencil_util.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
+#include "MOD_gpencil_legacy_ui_common.h"
+#include "MOD_gpencil_legacy_util.h"
 
 static void initData(GpencilModifierData *md)
 {
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpenciltexture.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_texture.c
similarity index 98%
rename from source/blender/gpencil_modifiers/intern/MOD_gpenciltexture.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_texture.c
index 1b7efc79457..b19f4f739cc 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpenciltexture.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_texture.c
@@ -35,9 +35,9 @@
 
 #include "RNA_access.h"
 
-#include "MOD_gpencil_modifiertypes.h"
-#include "MOD_gpencil_ui_common.h"
-#include "MOD_gpencil_util.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
+#include "MOD_gpencil_legacy_ui_common.h"
+#include "MOD_gpencil_legacy_util.h"
 
 static void initData(GpencilModifierData *md)
 {
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencilthick.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_thick.c
similarity index 98%
rename from source/blender/gpencil_modifiers/intern/MOD_gpencilthick.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_thick.c
index ea754ef8b20..1ebca18bcde 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencilthick.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_thick.c
@@ -35,9 +35,9 @@
 
 #include "RNA_access.h"
 
-#include "MOD_gpencil_modifiertypes.h"
-#include "MOD_gpencil_ui_common.h"
-#include "MOD_gpencil_util.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
+#include "MOD_gpencil_legacy_ui_common.h"
+#include "MOD_gpencil_legacy_util.h"
 
 static void initData(GpencilModifierData *md)
 {
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpenciltime.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_time.c
similarity index 99%
rename from source/blender/gpencil_modifiers/intern/MOD_gpenciltime.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_time.c
index 4ef6dd2c30a..83d5da1ef2b 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpenciltime.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_time.c
@@ -38,9 +38,9 @@
 #include "RNA_access.h"
 #include "RNA_prototypes.h"
 
-#include "MOD_gpencil_modifiertypes.h"
-#include "MOD_gpencil_ui_common.h"
-#include "MOD_gpencil_util.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
+#include "MOD_gpencil_legacy_ui_common.h"
+#include "MOD_gpencil_legacy_util.h"
 
 #include "UI_interface.h"
 #include "UI_resources.h"
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpenciltint.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_tint.c
similarity index 99%
rename from source/blender/gpencil_modifiers/intern/MOD_gpenciltint.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_tint.c
index da9a833e390..499d490d135 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpenciltint.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_tint.c
@@ -43,9 +43,9 @@
 
 #include "RNA_access.h"
 
-#include "MOD_gpencil_modifiertypes.h"
-#include "MOD_gpencil_ui_common.h"
-#include "MOD_gpencil_util.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
+#include "MOD_gpencil_legacy_ui_common.h"
+#include "MOD_gpencil_legacy_util.h"
 
 #include "DEG_depsgraph.h"
 #include "DEG_depsgraph_build.h"
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencil_ui_common.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_ui_common.c
similarity index 99%
rename from source/blender/gpencil_modifiers/intern/MOD_gpencil_ui_common.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_ui_common.c
index 1605da90c6c..424d2a37010 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencil_ui_common.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_ui_common.c
@@ -31,7 +31,7 @@
 #include "WM_api.h"
 #include "WM_types.h"
 
-#include "MOD_gpencil_ui_common.h" /* Self include */
+#include "MOD_gpencil_legacy_ui_common.h" /* Self include */
 
 /**
  * Poll function so these modifier panels only show for grease pencil objects.
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencil_ui_common.h b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_ui_common.h
similarity index 97%
rename from source/blender/gpencil_modifiers/intern/MOD_gpencil_ui_common.h
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_ui_common.h
index 57eac4d77bf..bb3a58a5254 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencil_ui_common.h
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_ui_common.h
@@ -10,7 +10,7 @@
 extern "C" {
 #endif
 
-#include "MOD_gpencil_modifiertypes.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
 
 struct ARegionType;
 struct PanelType;
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencil_util.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_util.c
similarity index 98%
rename from source/blender/gpencil_modifiers/intern/MOD_gpencil_util.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_util.c
index 8707eae7fa6..ddd043ea87a 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencil_util.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_util.c
@@ -23,8 +23,8 @@
 #include "BKE_material.h"
 #include "BKE_scene.h"
 
-#include "MOD_gpencil_modifiertypes.h"
-#include "MOD_gpencil_util.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
+#include "MOD_gpencil_legacy_util.h"
 
 #include "DEG_depsgraph_query.h"
 
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencil_util.h b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_util.h
similarity index 100%
rename from source/blender/gpencil_modifiers/intern/MOD_gpencil_util.h
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_util.h
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencilweight_angle.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_weight_angle.c
similarity index 98%
rename from source/blender/gpencil_modifiers/intern/MOD_gpencilweight_angle.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_weight_angle.c
index 237fc6e5afb..916298e2f17 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencilweight_angle.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_weight_angle.c
@@ -36,9 +36,9 @@
 
 #include "RNA_access.h"
 
-#include "MOD_gpencil_modifiertypes.h"
-#include "MOD_gpencil_ui_common.h"
-#include "MOD_gpencil_util.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
+#include "MOD_gpencil_legacy_ui_common.h"
+#include "MOD_gpencil_legacy_util.h"
 
 static void initData(GpencilModifierData *md)
 {
diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencilweight_proximity.c b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_weight_proximity.c
similarity index 98%
rename from source/blender/gpencil_modifiers/intern/MOD_gpencilweight_proximity.c
rename to source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_weight_proximity.c
index 76d2d1692bc..d1bfb65e6b7 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencilweight_proximity.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/MOD_gpencil_legacy_weight_proximity.c
@@ -37,9 +37,9 @@
 
 #include "RNA_access.h"
 
-#include "MOD_gpencil_modifiertypes.h"
-#include "MOD_gpencil_ui_common.h"
-#include "MOD_gpencil_util.h"
+#include "MOD_gpencil_legacy_modifiertypes.h"
+#include "MOD_gpencil_legacy_ui_common.h"
+#include "MOD_gpencil_legacy_util.h"
 
 static void initData(GpencilModifierData *md)
 {
diff --git a/source/blender/gpencil_modifiers/intern/lineart/MOD_lineart.h b/source/blender/gpencil_modifiers_legacy/intern/lineart/MOD_lineart.h
similarity index 100%
rename from source/blender/gpencil_modifiers/intern/lineart/MOD_lineart.h
rename to source/blender/gpencil_modifiers_legacy/intern/lineart/MOD_lineart.h
diff --git a/source/blender/gpencil_modifiers/intern/lineart/lineart_chain.c b/source/blender/gpencil_modifiers_legacy/intern/lineart/lineart_chain.c
similarity index 100%
rename from source/blender/gpencil_modifiers/intern/lineart/lineart_chain.c
rename to source/blender/gpencil_modifiers_legacy/intern/lineart/lineart_chain.c
diff --git a/source/blender/gpencil_modifiers/intern/lineart/lineart_cpu.cc b/source/blender/gpencil_modifiers_legacy/intern/lineart/lineart_cpu.cc
similarity index 99%
rename from source/blender/gpencil_modifiers/intern/lineart/lineart_cpu.cc
rename to source/blender/gpencil_modifiers_legacy/intern/lineart/lineart_cpu.cc
index c41139f1d9b..32e9eb4f714 100644
--- a/source/blender/gpencil_modifiers/intern/lineart/lineart_cpu.cc
+++ b/source/blender/gpencil_modifiers_legacy/intern/lineart/lineart_cpu.cc
@@ -5,7 +5,7 @@
  * \ingroup editors
  */
 
-#include "MOD_gpencil_lineart.h"
+#include "MOD_gpencil_legacy_lineart.h"
 #include "MOD_lineart.h"
 
 #include "BLI_edgehash.h"
diff --git a/source/blender/gpencil_modifiers/intern/lineart/lineart_intern.h b/source/blender/gpencil_modifiers_legacy/intern/lineart/lineart_intern.h
similarity index 100%
rename from source/blender/gpencil_modifiers/intern/lineart/lineart_intern.h
rename to source/blender/gpencil_modifiers_legacy/intern/lineart/lineart_intern.h
diff --git a/source/blender/gpencil_modifiers/intern/lineart/lineart_ops.c b/source/blender/gpencil_modifiers_legacy/intern/lineart/lineart_ops.c
similarity index 99%
rename from source/blender/gpencil_modifiers/intern/lineart/lineart_ops.c
rename to source/blender/gpencil_modifiers_legacy/intern/lineart/lineart_ops.c
index 19dee478ecd..be7b4be61af 100644
--- a/source/blender/gpencil_modifiers/intern/lineart/lineart_ops.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/lineart/lineart_ops.c
@@ -29,7 +29,7 @@
 #include "DNA_gpencil_modifier_types.h"
 #include "DNA_scene_types.h"
 
-#include "MOD_gpencil_lineart.h"
+#include "MOD_gpencil_legacy_lineart.h"
 #include "MOD_lineart.h"
 
 static bool lineart_mod_is_disabled(GpencilModifierData *md)
diff --git a/source/blender/gpencil_modifiers/intern/lineart/lineart_shadow.c b/source/blender/gpencil_modifiers_legacy/intern/lineart/lineart_shadow.c
similarity index 99%
rename from source/blender/gpencil_modifiers/intern/lineart/lineart_shadow.c
rename to source/blender/gpencil_modifiers_legacy/intern/lineart/lineart_shadow.c
index 1daea4a226b..54e5658f637 100644
--- a/source/blender/gpencil_modifiers/intern/lineart/lineart_shadow.c
+++ b/source/blender/gpencil_modifiers_legacy/intern/lineart/lineart_shadow.c
@@ -4,7 +4,7 @@
  * \ingroup modifiers
  */
 
-#include "MOD_gpencil_lineart.h"
+#include "MOD_gpencil_legacy_lineart.h"
 #include "MOD_lineart.h"
 
 #include "lineart_intern.h"
diff --git a/source/blender/gpencil_modifiers/intern/lineart/lineart_util.c b/source/blender/gpencil_modifiers_legacy/intern/lineart/lineart_util.c
similarity index 100%
rename from source/blender/gpencil_modifiers/intern/lineart/lineart_util.c
rename to source/blender/gpencil_modifiers_legacy/intern/lineart/lineart_util.c
diff --git a/source/blender/io/gpencil/intern/gpencil_io_export_pdf.cc b/source/blender/io/gpencil/intern/gpencil_io_export_pdf.cc
index 1955bf2f948..e9378e6c225 100644
--- a/source/blender/io/gpencil/intern/gpencil_io_export_pdf.cc
+++ b/source/blender/io/gpencil/intern/gpencil_io_export_pdf.cc
@@ -23,7 +23,7 @@
 #include "DEG_depsgraph.h"
 #include "DEG_depsgraph_query.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_view3d.h"
 
 #ifdef WIN32
diff --git a/source/blender/io/gpencil/intern/gpencil_io_export_svg.cc b/source/blender/io/gpencil/intern/gpencil_io_export_svg.cc
index d2d79e9cb33..1e6f688837d 100644
--- a/source/blender/io/gpencil/intern/gpencil_io_export_svg.cc
+++ b/source/blender/io/gpencil/intern/gpencil_io_export_svg.cc
@@ -23,7 +23,7 @@
 #include "DEG_depsgraph.h"
 #include "DEG_depsgraph_query.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_view3d.h"
 
 #ifdef WIN32
diff --git a/source/blender/io/gpencil/intern/gpencil_io_import_base.cc b/source/blender/io/gpencil/intern/gpencil_io_import_base.cc
index 4624ee23553..d63d546074b 100644
--- a/source/blender/io/gpencil/intern/gpencil_io_import_base.cc
+++ b/source/blender/io/gpencil/intern/gpencil_io_import_base.cc
@@ -13,7 +13,7 @@
 #include "BKE_gpencil_legacy.h"
 #include "BKE_material.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_object.h"
 
 #include "gpencil_io_import_base.hh"
diff --git a/source/blender/io/gpencil/intern/gpencil_io_import_svg.cc b/source/blender/io/gpencil/intern/gpencil_io_import_svg.cc
index f90d6f33a5b..34661027fd4 100644
--- a/source/blender/io/gpencil/intern/gpencil_io_import_svg.cc
+++ b/source/blender/io/gpencil/intern/gpencil_io_import_svg.cc
@@ -17,7 +17,7 @@
 #include "DEG_depsgraph.h"
 #include "DEG_depsgraph_query.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 
 #include "gpencil_io.h"
 #include "gpencil_io_import_svg.hh"
diff --git a/source/blender/io/usd/intern/usd_reader_mesh.cc b/source/blender/io/usd/intern/usd_reader_mesh.cc
index 4df4f7d566a..762686331f8 100644
--- a/source/blender/io/usd/intern/usd_reader_mesh.cc
+++ b/source/blender/io/usd/intern/usd_reader_mesh.cc
@@ -25,6 +25,9 @@
 #include "DNA_meshdata_types.h"
 #include "DNA_modifier_types.h"
 #include "DNA_object_types.h"
+#include "DNA_windowmanager_types.h"
+
+#include "WM_api.h"
 
 #include "MEM_guardedalloc.h"
 
@@ -408,102 +411,191 @@ void USDMeshReader::read_uvs(Mesh *mesh, const double motionSampleTime, const bo
   }
 }
 
-void USDMeshReader::read_colors(Mesh *mesh, const double motionSampleTime)
+void USDMeshReader::read_color_data_all_primvars(Mesh *mesh, const double motionSampleTime)
 {
   if (!(mesh && mesh_prim_ && mesh->totloop > 0)) {
     return;
   }
 
-  /* Early out if we read the display color before and if this attribute isn't animated. */
-  if (primvar_varying_map_.find(usdtokens::displayColor) != primvar_varying_map_.end() &&
-      !primvar_varying_map_.at(usdtokens::displayColor)) {
+  pxr::UsdGeomPrimvarsAPI pv_api = pxr::UsdGeomPrimvarsAPI(mesh_prim_);
+  std::vector<pxr::UsdGeomPrimvar> primvars = pv_api.GetPrimvarsWithValues();
+
+  pxr::TfToken active_color_name;
+
+  /* Convert color primvars to custom layer data. */
+  for (pxr::UsdGeomPrimvar &pv : primvars) {
+    if (!pv.HasValue()) {
+      continue;
+    }
+
+    pxr::SdfValueTypeName type = pv.GetTypeName();
+
+    if (!ELEM(type,
+              pxr::SdfValueTypeNames->Color3hArray,
+              pxr::SdfValueTypeNames->Color3fArray,
+              pxr::SdfValueTypeNames->Color3dArray)) {
+      continue;
+    }
+
+    pxr::TfToken name = pv.GetPrimvarName();
+
+    /* Set the active color name to 'displayColor', if a color primvar
+     * with this name exists.  Otherwise, use the name of the first
+     * color primvar we find for the active color. */
+    if (active_color_name.IsEmpty() || name == usdtokens::displayColor) {
+      active_color_name = name;
+    }
+
+    /* Skip if we read this primvar before and it isn't animated. */
+    const std::map<const pxr::TfToken, bool>::const_iterator is_animated_iter =
+        primvar_varying_map_.find(name);
+    if (is_animated_iter != primvar_varying_map_.end() && !is_animated_iter->second) {
+      continue;
+    }
+
+    read_color_data_primvar(mesh, pv, motionSampleTime);
+  }
+
+  if (!active_color_name.IsEmpty()) {
+    BKE_id_attributes_default_color_set(&mesh->id, active_color_name.GetText());
+    BKE_id_attributes_active_color_set(&mesh->id, active_color_name.GetText());
+  }
+}
+
+void USDMeshReader::read_color_data_primvar(Mesh *mesh,
+                                            const pxr::UsdGeomPrimvar &color_primvar,
+                                            const double motionSampleTime)
+{
+  if (!(mesh && color_primvar && color_primvar.HasValue())) {
     return;
   }
 
-  pxr::UsdGeomPrimvar color_primvar = mesh_prim_.GetDisplayColorPrimvar();
-
-  if (!color_primvar.HasValue()) {
-    return;
-  }
-
-  pxr::TfToken interp = color_primvar.GetInterpolation();
-
-  if (interp == pxr::UsdGeomTokens->varying) {
-    std::cerr << "WARNING: Unsupported varying interpolation for display colors\n" << std::endl;
-    return;
-  }
-
-  if (primvar_varying_map_.find(usdtokens::displayColor) == primvar_varying_map_.end()) {
+  if (primvar_varying_map_.find(color_primvar.GetPrimvarName()) == primvar_varying_map_.end()) {
     bool might_be_time_varying = color_primvar.ValueMightBeTimeVarying();
-    primvar_varying_map_.insert(std::make_pair(usdtokens::displayColor, might_be_time_varying));
+    primvar_varying_map_.insert(
+        std::make_pair(color_primvar.GetPrimvarName(), might_be_time_varying));
     if (might_be_time_varying) {
       is_time_varying_ = true;
     }
   }
 
-  pxr::VtArray<pxr::GfVec3f> display_colors;
+  pxr::VtArray<pxr::GfVec3f> usd_colors;
 
-  if (!color_primvar.ComputeFlattened(&display_colors, motionSampleTime)) {
-    std::cerr << "WARNING: Couldn't compute display colors\n" << std::endl;
+  if (!color_primvar.ComputeFlattened(&usd_colors, motionSampleTime)) {
+    WM_reportf(RPT_WARNING,
+               "USD Import: couldn't compute values for color attribute '%s'",
+               color_primvar.GetName().GetText());
     return;
   }
 
-  if ((interp == pxr::UsdGeomTokens->faceVarying && display_colors.size() != mesh->totloop) ||
-      (interp == pxr::UsdGeomTokens->vertex && display_colors.size() != mesh->totvert) ||
-      (interp == pxr::UsdGeomTokens->constant && display_colors.size() != 1) ||
-      (interp == pxr::UsdGeomTokens->uniform && display_colors.size() != mesh->totpoly)) {
-    std::cerr << "WARNING: display colors count mismatch\n" << std::endl;
+  pxr::TfToken interp = color_primvar.GetInterpolation();
+
+  if ((interp == pxr::UsdGeomTokens->faceVarying && usd_colors.size() != mesh->totloop) ||
+      (interp == pxr::UsdGeomTokens->varying && usd_colors.size() != mesh->totloop) ||
+      (interp == pxr::UsdGeomTokens->vertex && usd_colors.size() != mesh->totvert) ||
+      (interp == pxr::UsdGeomTokens->constant && usd_colors.size() != 1) ||
+      (interp == pxr::UsdGeomTokens->uniform && usd_colors.size() != mesh->totpoly)) {
+    WM_reportf(RPT_WARNING,
+               "USD Import: color attribute value '%s' count inconsistent with interpolation type",
+               color_primvar.GetName().GetText());
     return;
   }
 
-  void *cd_ptr = add_customdata_cb(mesh, "displayColor", CD_PROP_BYTE_COLOR);
+  const StringRef color_primvar_name(color_primvar.GetBaseName().GetString());
+  bke::MutableAttributeAccessor attributes = mesh->attributes_for_write();
 
-  if (!cd_ptr) {
-    std::cerr << "WARNING: Couldn't add displayColor custom data.\n";
+  eAttrDomain color_domain = ATTR_DOMAIN_POINT;
+
+  if (ELEM(interp,
+           pxr::UsdGeomTokens->varying,
+           pxr::UsdGeomTokens->faceVarying,
+           pxr::UsdGeomTokens->uniform)) {
+    color_domain = ATTR_DOMAIN_CORNER;
+  }
+
+  bke::SpanAttributeWriter<ColorGeometry4f> color_data;
+  color_data = attributes.lookup_or_add_for_write_only_span<ColorGeometry4f>(color_primvar_name,
+                                                                             color_domain);
+  if (!color_data) {
+    WM_reportf(RPT_WARNING,
+               "USD Import: couldn't add color attribute '%s'",
+               color_primvar.GetBaseName().GetText());
     return;
   }
 
-  MLoopCol *colors = static_cast<MLoopCol *>(cd_ptr);
-
-  const OffsetIndices polys = mesh->polys();
-  const Span<int> corner_verts = mesh->corner_verts();
-  for (const int i : polys.index_range()) {
-    const IndexRange poly = polys[i];
-    for (int j = 0; j < poly.size(); ++j) {
-      int loop_index = poly[j];
-
-      /* Default for constant varying interpolation. */
-      int usd_index = 0;
-
-      if (interp == pxr::UsdGeomTokens->vertex) {
-        usd_index = corner_verts[loop_index];
+  if (ELEM(interp, pxr::UsdGeomTokens->constant, pxr::UsdGeomTokens->uniform)) {
+    /* For situations where there's only a single item, flood fill the object. */
+    color_data.span.fill(
+        ColorGeometry4f(usd_colors[0][0], usd_colors[0][1], usd_colors[0][2], 1.0f));
+  }
+  else {
+    /* Check for situations that allow for a straight-forward copy by index. */
+    if ((ELEM(interp, pxr::UsdGeomTokens->vertex)) ||
+        (color_domain == ATTR_DOMAIN_CORNER && !is_left_handed_)) {
+      for (int i = 0; i < usd_colors.size(); i++) {
+        ColorGeometry4f color = ColorGeometry4f(
+            usd_colors[i][0], usd_colors[i][1], usd_colors[i][2], 1.0f);
+        color_data.span[i] = color;
       }
-      else if (interp == pxr::UsdGeomTokens->faceVarying) {
-        usd_index = poly.start();
-        if (is_left_handed_) {
-          usd_index += poly.size() - 1 - j;
-        }
-        else {
-          usd_index += j;
+    }
+
+    /* Special case: expand uniform color into corner color.
+     * Uniforms in USD come through as single colors, face-varying. Since Blender does not
+     * support this particular combination for paintable color attributes, we convert the type
+     * here to make sure that the user gets the same visual result.
+     * */
+    else if (ELEM(interp, pxr::UsdGeomTokens->uniform)) {
+      for (int i = 0; i < usd_colors.size(); i++) {
+        const ColorGeometry4f color = ColorGeometry4f(
+            usd_colors[i][0], usd_colors[i][1], usd_colors[i][2], 1.0f);
+        color_data.span[i * 4] = color;
+        color_data.span[i * 4 + 1] = color;
+        color_data.span[i * 4 + 2] = color;
+        color_data.span[i * 4 + 3] = color;
+      }
+    }
+
+    else {
+      const OffsetIndices polys = mesh->polys();
+      const Span<int> corner_verts = mesh->corner_verts();
+      for (const int i : polys.index_range()) {
+        const IndexRange &poly = polys[i];
+        for (int j = 0; j < poly.size(); ++j) {
+          int loop_index = poly[j];
+
+          /* Default for constant varying interpolation. */
+          int usd_index = 0;
+
+          if (interp == pxr::UsdGeomTokens->vertex) {
+            usd_index = corner_verts[loop_index];
+          }
+          else if (interp == pxr::UsdGeomTokens->faceVarying) {
+            usd_index = poly.start();
+            if (is_left_handed_) {
+              usd_index += poly.size() - 1 - j;
+            }
+            else {
+              usd_index += j;
+            }
+          }
+          else if (interp == pxr::UsdGeomTokens->uniform) {
+            /* Uniform varying uses the poly index. */
+            usd_index = i;
+          }
+
+          if (usd_index >= usd_colors.size()) {
+            continue;
+          }
+
+          ColorGeometry4f color = ColorGeometry4f(
+              usd_colors[usd_index][0], usd_colors[usd_index][1], usd_colors[usd_index][2], 1.0f);
+          color_data.span[usd_index] = color;
         }
       }
-      else if (interp == pxr::UsdGeomTokens->uniform) {
-        /* Uniform varying uses the poly index. */
-        usd_index = i;
-      }
-
-      if (usd_index >= display_colors.size()) {
-        continue;
-      }
-
-      colors[loop_index].r = unit_float_to_uchar_clamp(display_colors[usd_index][0]);
-      colors[loop_index].g = unit_float_to_uchar_clamp(display_colors[usd_index][1]);
-      colors[loop_index].b = unit_float_to_uchar_clamp(display_colors[usd_index][2]);
-      colors[loop_index].a = unit_float_to_uchar_clamp(1.0);
     }
   }
 
-  BKE_id_attributes_active_color_set(&mesh->id, "displayColor");
+  color_data.finish();
 }
 
 void USDMeshReader::read_vertex_creases(Mesh *mesh, const double motionSampleTime)
@@ -672,9 +764,19 @@ void USDMeshReader::read_mesh_sample(ImportSettings *settings,
     read_uvs(mesh, motionSampleTime, new_mesh);
   }
 
+  /* Custom Data layers. */
+  read_custom_data(settings, mesh, motionSampleTime);
+}
+
+void USDMeshReader::read_custom_data(const ImportSettings *settings,
+                                     Mesh *mesh,
+                                     const double motionSampleTime)
+{
   if ((settings->read_flag & MOD_MESHSEQ_READ_COLOR) != 0) {
-    read_colors(mesh, motionSampleTime);
+    read_color_data_all_primvars(mesh, motionSampleTime);
   }
+
+  /* TODO: Generic readers for custom data layers not listed above. */
 }
 
 void USDMeshReader::assign_facesets_to_material_indices(double motionSampleTime,
diff --git a/source/blender/io/usd/intern/usd_reader_mesh.h b/source/blender/io/usd/intern/usd_reader_mesh.h
index 0cabae2a653..7d5c512de1e 100644
--- a/source/blender/io/usd/intern/usd_reader_mesh.h
+++ b/source/blender/io/usd/intern/usd_reader_mesh.h
@@ -66,13 +66,20 @@ class USDMeshReader : public USDGeomReader {
 
   void read_mpolys(Mesh *mesh);
   void read_uvs(Mesh *mesh, double motionSampleTime, bool load_uvs = false);
-  void read_colors(Mesh *mesh, double motionSampleTime);
   void read_vertex_creases(Mesh *mesh, double motionSampleTime);
 
   void read_mesh_sample(ImportSettings *settings,
                         Mesh *mesh,
                         double motionSampleTime,
                         bool new_mesh);
+
+  void read_custom_data(const ImportSettings *settings,
+                        Mesh *mesh,
+                        double motionSampleTime);
+
+  void read_color_data_all_primvars(Mesh *mesh, const double motionSampleTime);
+  void read_color_data_primvar(Mesh *mesh, const pxr::UsdGeomPrimvar &color_primvar,
+                               const double motionSampleTime);
 };
 
 }  // namespace blender::io::usd
diff --git a/source/blender/io/usd/intern/usd_writer_mesh.cc b/source/blender/io/usd/intern/usd_writer_mesh.cc
index 885b34eb5ba..305b10c8a8a 100644
--- a/source/blender/io/usd/intern/usd_writer_mesh.cc
+++ b/source/blender/io/usd/intern/usd_writer_mesh.cc
@@ -14,7 +14,6 @@
 #include "BLI_math_vector_types.hh"
 
 #include "BKE_attribute.h"
-#include "BKE_attribute.hh"
 #include "BKE_customdata.h"
 #include "BKE_lib_id.h"
 #include "BKE_material.h"
@@ -32,6 +31,8 @@
 #include "DNA_object_fluidsim_types.h"
 #include "DNA_particle_types.h"
 
+#include "WM_api.h"
+
 #include <iostream>
 
 namespace blender::io::usd {
@@ -73,6 +74,72 @@ void USDGenericMeshWriter::do_write(HierarchyContext &context)
   }
 }
 
+void USDGenericMeshWriter::write_custom_data(const Mesh *mesh, pxr::UsdGeomMesh usd_mesh)
+{
+  const bke::AttributeAccessor attributes = mesh->attributes();
+
+  attributes.for_all(
+      [&](const bke::AttributeIDRef &attribute_id, const bke::AttributeMetaData &meta_data) {
+        /* Color data. */
+        if (ELEM(meta_data.domain, ATTR_DOMAIN_CORNER, ATTR_DOMAIN_POINT) &&
+            ELEM(meta_data.data_type, CD_PROP_BYTE_COLOR, CD_PROP_COLOR)) {
+          write_color_data(mesh, usd_mesh, attribute_id, meta_data);
+        }
+
+        return true;
+      });
+}
+
+void USDGenericMeshWriter::write_color_data(const Mesh *mesh,
+                                            pxr::UsdGeomMesh usd_mesh,
+                                            const bke::AttributeIDRef &attribute_id,
+                                            const bke::AttributeMetaData &meta_data)
+{
+  pxr::UsdTimeCode timecode = get_export_time_code();
+  const std::string name = attribute_id.name();
+  pxr::TfToken primvar_name(pxr::TfMakeValidIdentifier(name));
+  const pxr::UsdGeomPrimvarsAPI pvApi = pxr::UsdGeomPrimvarsAPI(usd_mesh);
+
+  /* Varying type depends on original domain. */
+  const pxr::TfToken prim_varying = meta_data.domain == ATTR_DOMAIN_CORNER ?
+                                        pxr::UsdGeomTokens->faceVarying :
+                                        pxr::UsdGeomTokens->vertex;
+
+  pxr::UsdGeomPrimvar colors_pv = pvApi.CreatePrimvar(
+      primvar_name, pxr::SdfValueTypeNames->Color3fArray, prim_varying);
+
+  const VArray<ColorGeometry4f> attribute = mesh->attributes().lookup_or_default<ColorGeometry4f>(
+      attribute_id, meta_data.domain, {0.0f, 0.0f, 0.0f, 1.0f});
+
+  pxr::VtArray<pxr::GfVec3f> colors_data;
+
+  /* TODO: Thread the copy, like the obj exporter. */
+  switch (meta_data.domain) {
+    case ATTR_DOMAIN_CORNER:
+      for (size_t loop_idx = 0; loop_idx < mesh->totloop; loop_idx++) {
+        const ColorGeometry4f color = attribute.get(loop_idx);
+        colors_data.push_back(pxr::GfVec3f(color.r, color.g, color.b));
+      }
+      break;
+
+    case ATTR_DOMAIN_POINT:
+      for (const int point_index : attribute.index_range()) {
+        const ColorGeometry4f color = attribute.get(point_index);
+        colors_data.push_back(pxr::GfVec3f(color.r, color.g, color.b));
+      }
+      break;
+
+    default:
+      BLI_assert_msg(0, "Invalid domain for mesh color data.");
+      return;
+  }
+
+  colors_pv.Set(colors_data, timecode);
+
+  const pxr::UsdAttribute &prim_colors_attr = colors_pv.GetAttr();
+  usd_value_writer_.SetAttribute(prim_colors_attr, pxr::VtValue(colors_data), timecode);
+}
+
 void USDGenericMeshWriter::free_export_mesh(Mesh *mesh)
 {
   BKE_id_free(nullptr, mesh);
@@ -233,6 +300,9 @@ void USDGenericMeshWriter::write_mesh(HierarchyContext &context, Mesh *mesh)
   if (usd_export_context_.export_params.export_uvmaps) {
     write_uv_maps(mesh, usd_mesh);
   }
+
+  write_custom_data(mesh, usd_mesh);
+
   if (usd_export_context_.export_params.export_normals) {
     write_normals(mesh, usd_mesh);
   }
diff --git a/source/blender/io/usd/intern/usd_writer_mesh.h b/source/blender/io/usd/intern/usd_writer_mesh.h
index 4abfa69aaa9..723835f4cd2 100644
--- a/source/blender/io/usd/intern/usd_writer_mesh.h
+++ b/source/blender/io/usd/intern/usd_writer_mesh.h
@@ -4,6 +4,8 @@
 
 #include "usd_writer_abstract.h"
 
+#include "BKE_attribute.hh"
+
 #include <pxr/usd/usdGeom/mesh.h>
 
 namespace blender::io::usd {
@@ -34,6 +36,12 @@ class USDGenericMeshWriter : public USDAbstractWriter {
   void write_uv_maps(const Mesh *mesh, pxr::UsdGeomMesh usd_mesh);
   void write_normals(const Mesh *mesh, pxr::UsdGeomMesh usd_mesh);
   void write_surface_velocity(const Mesh *mesh, pxr::UsdGeomMesh usd_mesh);
+
+  void write_custom_data(const Mesh *mesh, pxr::UsdGeomMesh usd_mesh);
+  void write_color_data(const Mesh *mesh,
+                        pxr::UsdGeomMesh usd_mesh,
+                        const bke::AttributeIDRef &attribute_id,
+                        const bke::AttributeMetaData &meta_data);
 };
 
 class USDMeshWriter : public USDGenericMeshWriter {
diff --git a/source/blender/makesdna/DNA_curves_types.h b/source/blender/makesdna/DNA_curves_types.h
index cef5f70b732..a92ba92d2cd 100644
--- a/source/blender/makesdna/DNA_curves_types.h
+++ b/source/blender/makesdna/DNA_curves_types.h
@@ -107,6 +107,9 @@ typedef struct CurvesGeometry {
    * Every curve offset must be at least one larger than the previous. In other words, every curve
    * must have at least one point. The first value is 0 and the last value is #point_num.
    *
+   * This array is shared based on the bke::MeshRuntime::poly_offsets_sharing_info.
+   * Avoid accessing directly when possible.
+   *
    * \note This is *not* stored as an attribute because its size is one larger than #curve_num.
    */
   int *curve_offsets;
diff --git a/source/blender/makesdna/DNA_customdata_types.h b/source/blender/makesdna/DNA_customdata_types.h
index 816d39965ee..305c8ecfc1d 100644
--- a/source/blender/makesdna/DNA_customdata_types.h
+++ b/source/blender/makesdna/DNA_customdata_types.h
@@ -104,8 +104,8 @@ typedef enum eCustomDataType {
   CD_AUTO_FROM_NAME = -1,
 
 #ifdef DNA_DEPRECATED_ALLOW
-  CD_MVERT = 0,   /* DEPRECATED */
-  CD_MSTICKY = 1, /* DEPRECATED */
+  CD_MVERT = 0,
+  CD_MSTICKY = 1,
 #endif
   CD_MDEFORMVERT = 2, /* Array of `MDeformVert`. */
   CD_MEDGE = 3,
@@ -125,9 +125,9 @@ typedef enum eCustomDataType {
   CD_ORIGSPACE = 13, /* for modifier stack face location mapping */
   CD_ORCO = 14,      /* undeformed vertex coordinates, normalized to 0..1 range */
 #ifdef DNA_DEPRECATED_ALLOW
-  CD_MTEXPOLY = 15, /* deprecated */
-#endif
+  CD_MTEXPOLY = 15,
   CD_MLOOPUV = 16,
+#endif
   CD_PROP_BYTE_COLOR = 17,
   CD_TANGENT = 18,
   CD_MDISPS = 19,
@@ -138,7 +138,9 @@ typedef enum eCustomDataType {
   /* CD_RECAST = 24, */ /* UNUSED */
 
   CD_MPOLY = 25,
+#ifdef DNA_DEPRECATED_ALLOW
   CD_MLOOP = 26,
+#endif
   CD_SHAPE_KEYINDEX = 27,
   CD_SHAPEKEY = 28,
   CD_BWEIGHT = 29,
@@ -156,12 +158,15 @@ typedef enum eCustomDataType {
   CD_MLOOPTANGENT = 39,
   CD_TESSLOOPNORMAL = 40,
   CD_CUSTOMLOOPNORMAL = 41,
+#ifdef DNA_DEPRECATED_ALLOW
   CD_SCULPT_FACE_SETS = 42,
+#endif
 
   /* CD_LOCATION = 43, */ /* UNUSED */
   /* CD_RADIUS = 44, */   /* UNUSED */
   CD_PROP_INT8 = 45,
-  /* CD_HAIRMAPPING = 46, */ /* UNUSED, can be reused. */
+  /* Two 32-bit signed integers. */
+  CD_PROP_INT32_2D = 46,
 
   CD_PROP_COLOR = 47,
   CD_PROP_FLOAT3 = 48,
@@ -174,8 +179,6 @@ typedef enum eCustomDataType {
 } eCustomDataType;
 
 /* Bits for eCustomDataMask */
-// #define CD_MASK_MVERT (1 << CD_MVERT) /* DEPRECATED */
-// #define CD_MASK_MSTICKY      (1 << CD_MSTICKY)  /* DEPRECATED */
 #define CD_MASK_MDEFORMVERT (1 << CD_MDEFORMVERT)
 #define CD_MASK_MEDGE (1 << CD_MEDGE)
 #define CD_MASK_MFACE (1 << CD_MFACE)
@@ -189,13 +192,11 @@ typedef enum eCustomDataType {
 #define CD_MASK_PROP_STRING (1 << CD_PROP_STRING)
 #define CD_MASK_ORIGSPACE (1 << CD_ORIGSPACE)
 #define CD_MASK_ORCO (1 << CD_ORCO)
-// #define CD_MASK_MTEXPOLY (1 << CD_MTEXPOLY)  /* DEPRECATED */
 #define CD_MASK_PROP_BYTE_COLOR (1 << CD_PROP_BYTE_COLOR)
 #define CD_MASK_TANGENT (1 << CD_TANGENT)
 #define CD_MASK_MDISPS (1 << CD_MDISPS)
 #define CD_MASK_PREVIEW_MCOL (1 << CD_PREVIEW_MCOL)
 #define CD_MASK_CLOTH_ORCO (1 << CD_CLOTH_ORCO)
-// #define CD_MASK_RECAST (1 << CD_RECAST)  /* DEPRECATED */
 
 #define CD_MASK_SHAPE_KEYINDEX (1 << CD_SHAPE_KEYINDEX)
 #define CD_MASK_SHAPEKEY (1 << CD_SHAPEKEY)
@@ -218,6 +219,7 @@ typedef enum eCustomDataType {
 #define CD_MASK_PROP_FLOAT2 (1ULL << CD_PROP_FLOAT2)
 #define CD_MASK_PROP_BOOL (1ULL << CD_PROP_BOOL)
 #define CD_MASK_PROP_INT8 (1ULL << CD_PROP_INT8)
+#define CD_MASK_PROP_INT32_2D (1ULL << CD_PROP_INT32_2D)
 
 #define CD_MASK_HAIRLENGTH (1ULL << CD_HAIRLENGTH)
 
@@ -231,7 +233,7 @@ typedef enum eCustomDataType {
 #define CD_MASK_PROP_ALL \
   (CD_MASK_PROP_FLOAT | CD_MASK_PROP_FLOAT2 | CD_MASK_PROP_FLOAT3 | CD_MASK_PROP_INT32 | \
    CD_MASK_PROP_COLOR | CD_MASK_PROP_STRING | CD_MASK_PROP_BYTE_COLOR | CD_MASK_PROP_BOOL | \
-   CD_MASK_PROP_INT8)
+   CD_MASK_PROP_INT8 | CD_MASK_PROP_INT32_2D)
 
 /* All color attributes */
 #define CD_MASK_COLOR_ALL (CD_MASK_PROP_COLOR | CD_MASK_PROP_BYTE_COLOR)
diff --git a/source/blender/makesdna/DNA_mesh_types.h b/source/blender/makesdna/DNA_mesh_types.h
index 50323233917..f0dbf6f86d9 100644
--- a/source/blender/makesdna/DNA_mesh_types.h
+++ b/source/blender/makesdna/DNA_mesh_types.h
@@ -78,6 +78,9 @@ typedef struct Mesh {
   /**
    * Array owned by mesh. May be null of there are no polygons. Index of the first corner of each
    * polygon, with the total number of corners at the end. See #Mesh::polys() and #OffsetIndices.
+   *
+   * This array is shared based on the bke::MeshRuntime::poly_offsets_sharing_info.
+   * Avoid accessing directly when possible.
    */
   int *poly_offset_indices;
 
diff --git a/source/blender/makesdna/DNA_space_types.h b/source/blender/makesdna/DNA_space_types.h
index 2bdb3f09583..d52e265b65e 100644
--- a/source/blender/makesdna/DNA_space_types.h
+++ b/source/blender/makesdna/DNA_space_types.h
@@ -1980,6 +1980,7 @@ typedef struct SpreadsheetRowFilter {
   char _pad0[2];
 
   int value_int;
+  int value_int2[2];
   char *value_string;
   float value_float;
   float threshold;
@@ -2025,6 +2026,7 @@ typedef enum eSpreadsheetColumnValueType {
   SPREADSHEET_VALUE_TYPE_STRING = 7,
   SPREADSHEET_VALUE_TYPE_BYTE_COLOR = 8,
   SPREADSHEET_VALUE_TYPE_INT8 = 9,
+  SPREADSHEET_VALUE_TYPE_INT32_2D = 10,
 } eSpreadsheetColumnValueType;
 
 /**
diff --git a/source/blender/makesdna/DNA_vec_types.h b/source/blender/makesdna/DNA_vec_types.h
index f053efff2b4..f9294ffe314 100644
--- a/source/blender/makesdna/DNA_vec_types.h
+++ b/source/blender/makesdna/DNA_vec_types.h
@@ -23,12 +23,12 @@ typedef struct vec2f {
   float x, y;
 } vec2f;
 
-/* not used at the moment */
-/*
 typedef struct vec2i {
   int x, y;
 } vec2i;
 
+/* not used at the moment */
+/*
 typedef struct vec2d {
   double x, y;
 } vec2d;
diff --git a/source/blender/makesrna/intern/CMakeLists.txt b/source/blender/makesrna/intern/CMakeLists.txt
index 5d5e5cdcbb3..04b3b1389ed 100644
--- a/source/blender/makesrna/intern/CMakeLists.txt
+++ b/source/blender/makesrna/intern/CMakeLists.txt
@@ -36,8 +36,8 @@ set(DEFSRC
   rna_dynamicpaint.c
   rna_fcurve.c
   rna_fluid.c
-  rna_gpencil.c
-  rna_gpencil_modifier.c
+  rna_gpencil_legacy.c
+  rna_gpencil_legacy_modifier.c
   rna_image.c
   rna_key.c
   rna_lattice.c
@@ -431,7 +431,7 @@ set(LIB
   bf_editor_curve
   bf_editor_curves
   bf_editor_gizmo_library
-  bf_editor_gpencil
+  bf_editor_gpencil_legacy
   bf_editor_io
   bf_editor_mesh
   bf_editor_object
diff --git a/source/blender/makesrna/intern/makesrna.c b/source/blender/makesrna/intern/makesrna.c
index a5ede32ec34..3cf32a878dc 100644
--- a/source/blender/makesrna/intern/makesrna.c
+++ b/source/blender/makesrna/intern/makesrna.c
@@ -4515,7 +4515,7 @@ static RNAProcessItem PROCESS_ITEMS[] = {
     {"rna_curve.c", "rna_curve_api.c", RNA_def_curve},
     {"rna_dynamicpaint.c", NULL, RNA_def_dynamic_paint},
     {"rna_fcurve.c", "rna_fcurve_api.c", RNA_def_fcurve},
-    {"rna_gpencil.c", NULL, RNA_def_gpencil},
+    {"rna_gpencil_legacy.c", NULL, RNA_def_gpencil},
     {"rna_curves.c", NULL, RNA_def_curves},
     {"rna_image.c", "rna_image_api.c", RNA_def_image},
     {"rna_key.c", NULL, RNA_def_key},
@@ -4529,7 +4529,7 @@ static RNAProcessItem PROCESS_ITEMS[] = {
     {"rna_mesh.c", "rna_mesh_api.c", RNA_def_mesh},
     {"rna_meta.c", "rna_meta_api.c", RNA_def_meta},
     {"rna_modifier.c", NULL, RNA_def_modifier},
-    {"rna_gpencil_modifier.c", NULL, RNA_def_greasepencil_modifier},
+    {"rna_gpencil_legacy_modifier.c", NULL, RNA_def_greasepencil_modifier},
     {"rna_shader_fx.c", NULL, RNA_def_shader_fx},
     {"rna_nla.c", NULL, RNA_def_nla},
     {"rna_nodetree.c", NULL, RNA_def_nodetree},
diff --git a/source/blender/makesrna/intern/rna_attribute.c b/source/blender/makesrna/intern/rna_attribute.c
index 3aedc92a248..b669ac0c888 100644
--- a/source/blender/makesrna/intern/rna_attribute.c
+++ b/source/blender/makesrna/intern/rna_attribute.c
@@ -39,6 +39,7 @@ const EnumPropertyItem rna_enum_attribute_type_items[] = {
     {CD_PROP_BOOL, "BOOLEAN", 0, "Boolean", "True or false"},
     {CD_PROP_FLOAT2, "FLOAT2", 0, "2D Vector", "2D vector with floating-point values"},
     {CD_PROP_INT8, "INT8", 0, "8-Bit Integer", "Smaller integer with a range from -128 to 127"},
+    {CD_PROP_INT32_2D, "INT32_2D", 0, "2D Integer Vector", "32-bit signed integer vector"},
     {0, NULL, 0, NULL, NULL},
 };
 
@@ -65,7 +66,8 @@ const EnumPropertyItem rna_enum_attribute_type_with_auto_items[] = {
     {CD_PROP_STRING, "STRING", 0, "String", "Text string"},
     {CD_PROP_BOOL, "BOOLEAN", 0, "Boolean", "True or false"},
     {CD_PROP_FLOAT2, "FLOAT2", 0, "2D Vector", "2D vector with floating-point values"},
-    {CD_PROP_INT8, "INT8", 0, "8-Bit Integer", "Smaller integer with a range from -128 to 127"},
+    {CD_PROP_FLOAT2, "FLOAT2", 0, "2D Vector", "2D vector with floating-point values"},
+    {CD_PROP_INT32_2D, "INT32_2D", 0, "2D Integer Vector", "32-bit signed integer vector"},
     {0, NULL, 0, NULL, NULL},
 };
 
@@ -162,6 +164,8 @@ static StructRNA *srna_by_custom_data_layer_type(const eCustomDataType type)
       return &RNA_Float2Attribute;
     case CD_PROP_INT8:
       return &RNA_ByteIntAttribute;
+    case CD_PROP_INT32_2D:
+      return &RNA_Int2Attribute;
     default:
       return NULL;
   }
@@ -292,6 +296,9 @@ static void rna_Attribute_data_begin(CollectionPropertyIterator *iter, PointerRN
     case CD_PROP_INT8:
       struct_size = sizeof(int8_t);
       break;
+    case CD_PROP_INT32_2D:
+      struct_size = sizeof(int[2]);
+      break;
     default:
       struct_size = 0;
       length = 0;
@@ -1017,6 +1024,40 @@ static void rna_def_attribute_int8(BlenderRNA *brna)
       prop, "rna_ByteIntAttributeValue_get", "rna_ByteIntAttributeValue_set", NULL);
 }
 
+static void rna_def_attribute_int2(BlenderRNA *brna)
+{
+  StructRNA *srna;
+  PropertyRNA *prop;
+
+  srna = RNA_def_struct(brna, "Int2Attribute", "Attribute");
+  RNA_def_struct_sdna(srna, "CustomDataLayer");
+  RNA_def_struct_ui_text(
+      srna, "2D Integer Vector Attribute", "Geometry attribute that stores 2D integer vectors");
+
+  prop = RNA_def_property(srna, "data", PROP_COLLECTION, PROP_NONE);
+  RNA_def_property_struct_type(prop, "Int2AttributeValue");
+  RNA_def_property_collection_funcs(prop,
+                                    "rna_Attribute_data_begin",
+                                    "rna_iterator_array_next",
+                                    "rna_iterator_array_end",
+                                    "rna_iterator_array_get",
+                                    "rna_Attribute_data_length",
+                                    NULL,
+                                    NULL,
+                                    NULL);
+
+  srna = RNA_def_struct(brna, "Int2AttributeValue", NULL);
+  RNA_def_struct_sdna(srna, "vec2i");
+  RNA_def_struct_ui_text(
+      srna, "2D Integer Vector Attribute Value", "2D value in geometry attribute");
+
+  prop = RNA_def_property(srna, "value", PROP_INT, PROP_NONE);
+  RNA_def_property_ui_text(prop, "Vector", "2D vector");
+  RNA_def_property_int_sdna(prop, NULL, "x");
+  RNA_def_property_array(prop, 2);
+  RNA_def_property_update(prop, 0, "rna_Attribute_update_data");
+}
+
 static void rna_def_attribute_float2(BlenderRNA *brna)
 {
   StructRNA *srna;
@@ -1095,6 +1136,7 @@ static void rna_def_attribute(BlenderRNA *brna)
   rna_def_attribute_float_color(brna);
   rna_def_attribute_byte_color(brna);
   rna_def_attribute_int(brna);
+  rna_def_attribute_int2(brna);
   rna_def_attribute_string(brna);
   rna_def_attribute_bool(brna);
   rna_def_attribute_float2(brna);
diff --git a/source/blender/makesrna/intern/rna_brush.c b/source/blender/makesrna/intern/rna_brush.c
index d145e7c9f5b..aa96102f74d 100644
--- a/source/blender/makesrna/intern/rna_brush.c
+++ b/source/blender/makesrna/intern/rna_brush.c
@@ -248,7 +248,7 @@ const EnumPropertyItem rna_enum_brush_gpencil_sculpt_types_items[] = {
      "CLONE",
      ICON_GPBRUSH_CLONE,
      "Clone",
-     "Paste copies of the strokes stored on the clipboard"},
+     "Paste copies of the strokes stored on the internal clipboard"},
     {0, NULL, 0, NULL, NULL}};
 
 const EnumPropertyItem rna_enum_brush_gpencil_weight_types_items[] = {
@@ -262,16 +262,18 @@ const EnumPropertyItem rna_enum_brush_gpencil_weight_types_items[] = {
 
 /* clang-format off */
 const EnumPropertyItem rna_enum_brush_curves_sculpt_tool_items[] = {
-    {CURVES_SCULPT_TOOL_COMB, "COMB", ICON_BRUSH_CURVES_COMB, "Comb Curves", ""},
-    {CURVES_SCULPT_TOOL_DELETE, "DELETE", ICON_BRUSH_CURVES_DELETE, "Delete Curves", ""},
-    {CURVES_SCULPT_TOOL_SNAKE_HOOK, "SNAKE_HOOK", ICON_BRUSH_CURVES_SNAKE_HOOK, "Curves Snake Hook", ""},
-    {CURVES_SCULPT_TOOL_ADD, "ADD", ICON_BRUSH_CURVES_ADD, "Add Curves", ""},
-    {CURVES_SCULPT_TOOL_GROW_SHRINK, "GROW_SHRINK", ICON_BRUSH_CURVES_GROW_SHRINK, "Grow / Shrink Curves", ""},
     {CURVES_SCULPT_TOOL_SELECTION_PAINT, "SELECTION_PAINT", ICON_BRUSH_PAINT_SELECT, "Paint Selection", ""},
-    {CURVES_SCULPT_TOOL_PINCH, "PINCH", ICON_BRUSH_CURVES_PINCH, "Pinch Curves", ""},
-    {CURVES_SCULPT_TOOL_SMOOTH, "SMOOTH", ICON_BRUSH_CURVES_SMOOTH, "Smooth Curves", ""},
-    {CURVES_SCULPT_TOOL_PUFF, "PUFF", ICON_BRUSH_CURVES_PUFF, "Puff Curves", ""},
+    RNA_ENUM_ITEM_SEPR,
+    {CURVES_SCULPT_TOOL_ADD, "ADD", ICON_BRUSH_CURVES_ADD, "Add Curves", ""},
+    {CURVES_SCULPT_TOOL_DELETE, "DELETE", ICON_BRUSH_CURVES_DELETE, "Delete Curves", ""},
     {CURVES_SCULPT_TOOL_DENSITY, "DENSITY", ICON_BRUSH_CURVES_DENSITY, "Density Curves", ""},
+    RNA_ENUM_ITEM_SEPR,
+    {CURVES_SCULPT_TOOL_COMB, "COMB", ICON_BRUSH_CURVES_COMB, "Comb Curves", ""},
+    {CURVES_SCULPT_TOOL_SNAKE_HOOK, "SNAKE_HOOK", ICON_BRUSH_CURVES_SNAKE_HOOK, "Curves Snake Hook", ""},
+    {CURVES_SCULPT_TOOL_GROW_SHRINK, "GROW_SHRINK", ICON_BRUSH_CURVES_GROW_SHRINK, "Grow / Shrink Curves", ""},
+    {CURVES_SCULPT_TOOL_PINCH, "PINCH", ICON_BRUSH_CURVES_PINCH, "Pinch Curves", ""},
+    {CURVES_SCULPT_TOOL_PUFF, "PUFF", ICON_BRUSH_CURVES_PUFF, "Puff Curves", ""},
+    {CURVES_SCULPT_TOOL_SMOOTH, "SMOOTH", ICON_BRUSH_CURVES_SMOOTH, "Smooth Curves", ""},
     {CURVES_SCULPT_TOOL_SLIDE, "SLIDE", ICON_BRUSH_CURVES_SLIDE, "Slide Curves", ""},
     {0, NULL, 0, NULL, NULL},
 };
diff --git a/source/blender/makesrna/intern/rna_curves.c b/source/blender/makesrna/intern/rna_curves.c
index b14fe826e62..bed608a5711 100644
--- a/source/blender/makesrna/intern/rna_curves.c
+++ b/source/blender/makesrna/intern/rna_curves.c
@@ -77,6 +77,18 @@ static void rna_Curves_curve_offset_data_begin(CollectionPropertyIterator *iter,
                            NULL);
 }
 
+static int rna_Curves_curve_offset_data_lookup_int(PointerRNA *ptr, int index, PointerRNA *r_ptr)
+{
+  Curves *curves = rna_curves(ptr);
+  if (index < 0 || index >= curves->geometry.curve_num + 1) {
+    return false;
+  }
+  r_ptr->owner_id = &curves->id;
+  r_ptr->type = &RNA_IntAttributeValue;
+  r_ptr->data = &ED_curves_offsets_for_write(curves)[index];
+  return true;
+}
+
 static float (*get_curves_positions(Curves *curves))[3]
 {
   return (float(*)[3])CustomData_get_layer_named_for_write(
@@ -97,6 +109,35 @@ static int rna_CurvePoint_index_get_const(const PointerRNA *ptr)
   return (int)(co - positions);
 }
 
+static void rna_Curves_curves_begin(CollectionPropertyIterator *iter, PointerRNA *ptr)
+{
+  Curves *curves = rna_curves(ptr);
+  rna_iterator_array_begin(iter,
+                           ED_curves_offsets_for_write(curves),
+                           sizeof(int),
+                           curves->geometry.curve_num,
+                           false,
+                           NULL);
+}
+
+static int rna_Curves_curves_length(PointerRNA *ptr)
+{
+  const Curves *curves = rna_curves(ptr);
+  return curves->geometry.curve_num;
+}
+
+static int rna_Curves_curves_lookup_int(PointerRNA *ptr, int index, PointerRNA *r_ptr)
+{
+  Curves *curves = rna_curves(ptr);
+  if (index < 0 || index >= curves->geometry.curve_num) {
+    return false;
+  }
+  r_ptr->owner_id = &curves->id;
+  r_ptr->type = &RNA_CurveSlice;
+  r_ptr->data = &ED_curves_offsets_for_write(curves)[index];
+  return true;
+}
+
 static int rna_Curves_position_data_length(PointerRNA *ptr)
 {
   const Curves *curves = rna_curves(ptr);
@@ -343,7 +384,15 @@ static void rna_def_curves(BlenderRNA *brna)
   /* Point and Curve RNA API helpers. */
 
   prop = RNA_def_property(srna, "curves", PROP_COLLECTION, PROP_NONE);
-  RNA_def_property_collection_sdna(prop, NULL, "geometry.curve_offsets", "geometry.curve_num");
+  RNA_def_property_collection_funcs(prop,
+                                    "rna_Curves_curves_begin",
+                                    "rna_iterator_array_next",
+                                    "rna_iterator_array_end",
+                                    "rna_iterator_array_get",
+                                    "rna_Curves_curves_length",
+                                    "rna_Curves_curves_lookup_int",
+                                    NULL,
+                                    NULL);
   RNA_def_property_struct_type(prop, "CurveSlice");
   RNA_def_property_ui_text(prop, "Curves", "All curves in the data-block");
 
@@ -376,7 +425,6 @@ static void rna_def_curves(BlenderRNA *brna)
   RNA_def_property_update(prop, 0, "rna_Curves_update_data");
 
   prop = RNA_def_property(srna, "curve_offset_data", PROP_COLLECTION, PROP_NONE);
-  RNA_def_property_collection_sdna(prop, NULL, "geometry.curve_offsets", NULL);
   RNA_def_property_struct_type(prop, "IntAttributeValue");
   RNA_def_property_collection_funcs(prop,
                                     "rna_Curves_curve_offset_data_begin",
@@ -384,7 +432,7 @@ static void rna_def_curves(BlenderRNA *brna)
                                     "rna_iterator_array_end",
                                     "rna_iterator_array_get",
                                     "rna_Curves_curve_offset_data_length",
-                                    NULL,
+                                    "rna_Curves_curve_offset_data_lookup_int",
                                     NULL,
                                     NULL);
   RNA_def_property_update(prop, 0, "rna_Curves_update_data");
diff --git a/source/blender/makesrna/intern/rna_gpencil.c b/source/blender/makesrna/intern/rna_gpencil_legacy.c
similarity index 100%
rename from source/blender/makesrna/intern/rna_gpencil.c
rename to source/blender/makesrna/intern/rna_gpencil_legacy.c
diff --git a/source/blender/makesrna/intern/rna_gpencil_modifier.c b/source/blender/makesrna/intern/rna_gpencil_legacy_modifier.c
similarity index 100%
rename from source/blender/makesrna/intern/rna_gpencil_modifier.c
rename to source/blender/makesrna/intern/rna_gpencil_legacy_modifier.c
diff --git a/source/blender/makesrna/intern/rna_main.c b/source/blender/makesrna/intern/rna_main.c
index e0128595b7f..dbb2b7e7071 100644
--- a/source/blender/makesrna/intern/rna_main.c
+++ b/source/blender/makesrna/intern/rna_main.c
@@ -332,8 +332,8 @@ void RNA_def_main(BlenderRNA *brna)
       {"grease_pencils",
        "GreasePencil",
        "rna_Main_gpencils_begin",
-       "Grease Pencil",
-       "Grease Pencil data-blocks",
+       "Grease Pencil (legacy)",
+       "Grease Pencil (legacy) data-blocks",
        RNA_def_main_gpencil},
       {"movieclips",
        "MovieClip",
diff --git a/source/blender/makesrna/intern/rna_material.c b/source/blender/makesrna/intern/rna_material.c
index 2b0c2a269dd..4221893e4c3 100644
--- a/source/blender/makesrna/intern/rna_material.c
+++ b/source/blender/makesrna/intern/rna_material.c
@@ -77,7 +77,7 @@ const EnumPropertyItem rna_enum_ramp_blend_items[] = {
 #  include "DEG_depsgraph.h"
 #  include "DEG_depsgraph_build.h"
 
-#  include "ED_gpencil.h"
+#  include "ED_gpencil_legacy.h"
 #  include "ED_image.h"
 #  include "ED_node.h"
 #  include "ED_screen.h"
diff --git a/source/blender/makesrna/intern/rna_rna.c b/source/blender/makesrna/intern/rna_rna.c
index 4f9cecc307e..ac264687cb4 100644
--- a/source/blender/makesrna/intern/rna_rna.c
+++ b/source/blender/makesrna/intern/rna_rna.c
@@ -1013,21 +1013,33 @@ static int rna_enum_check_separator(CollectionPropertyIterator *UNUSED(iter), vo
   return (item->identifier[0] == 0);
 }
 
-static void rna_EnumProperty_items_begin(CollectionPropertyIterator *iter, PointerRNA *ptr)
+static void rna_EnumProperty_items_begin_impl(CollectionPropertyIterator *iter,
+                                              PointerRNA *ptr,
+                                              IteratorSkipFunc skip_fn)
 {
   PropertyRNA *prop = (PropertyRNA *)ptr->data;
-  /* EnumPropertyRNA *eprop; */ /* UNUSED */
+  // EnumPropertyRNA *eprop; /* UNUSED */
   const EnumPropertyItem *item = NULL;
   int totitem;
   bool free;
 
   prop = rna_ensure_property(prop);
-  /* eprop = (EnumPropertyRNA *)prop; */
+  // eprop = (EnumPropertyRNA *)prop;
 
   RNA_property_enum_items_ex(
       NULL, ptr, prop, STREQ(iter->prop->identifier, "enum_items_static"), &item, &totitem, &free);
-  rna_iterator_array_begin(
-      iter, (void *)item, sizeof(EnumPropertyItem), totitem, free, rna_enum_check_separator);
+  rna_iterator_array_begin(iter, (void *)item, sizeof(EnumPropertyItem), totitem, free, skip_fn);
+}
+
+static void rna_EnumProperty_items_begin(CollectionPropertyIterator *iter, PointerRNA *ptr)
+{
+  rna_EnumProperty_items_begin_impl(iter, ptr, rna_enum_check_separator);
+}
+
+static void rna_EnumProperty_items_ui_begin(CollectionPropertyIterator *iter, PointerRNA *ptr)
+{
+  /* No skip-funciton, include all "UI" items. */
+  rna_EnumProperty_items_begin_impl(iter, ptr, NULL);
 }
 
 static void rna_EnumPropertyItem_identifier_get(PointerRNA *ptr, char *value)
@@ -3360,6 +3372,26 @@ static void rna_def_enum_property(BlenderRNA *brna, StructRNA *srna)
       "Static Items",
       "Possible values for the property (never calls optional dynamic generation of those)");
 
+  /* Expose a UI version of `enum_items_static` to allow separator & title access,
+   * needed for the tool-system to access separators from brush enums. */
+  prop = RNA_def_property(srna, "enum_items_static_ui", PROP_COLLECTION, PROP_NONE);
+  RNA_def_property_clear_flag(prop, PROP_EDITABLE);
+  RNA_def_property_struct_type(prop, "EnumPropertyItem");
+  RNA_def_property_collection_funcs(prop,
+                                    "rna_EnumProperty_items_ui_begin",
+                                    "rna_iterator_array_next",
+                                    "rna_iterator_array_end",
+                                    "rna_iterator_array_get",
+                                    NULL,
+                                    NULL,
+                                    NULL,
+                                    NULL);
+  RNA_def_property_ui_text(
+      prop,
+      "Static Items with UI Elements",
+      "Possible values for the property (never calls optional dynamic generation of those). "
+      "Includes UI elements (separators and section headings)");
+
   srna = RNA_def_struct(brna, "EnumPropertyItem", NULL);
   RNA_def_struct_ui_text(
       srna, "Enum Item Definition", "Definition of a choice in an RNA enum property");
diff --git a/source/blender/makesrna/intern/rna_scene.c b/source/blender/makesrna/intern/rna_scene.c
index fe8ec52f1ef..04d2d2e8c84 100644
--- a/source/blender/makesrna/intern/rna_scene.c
+++ b/source/blender/makesrna/intern/rna_scene.c
@@ -34,7 +34,7 @@
 #include "BKE_paint.h"
 #include "BKE_volume.h"
 
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_object.h"
 #include "ED_uvedit.h"
 
diff --git a/source/blender/makesrna/intern/rna_sculpt_paint.c b/source/blender/makesrna/intern/rna_sculpt_paint.c
index a468d2c5272..5b5b4dcfc25 100644
--- a/source/blender/makesrna/intern/rna_sculpt_paint.c
+++ b/source/blender/makesrna/intern/rna_sculpt_paint.c
@@ -116,7 +116,7 @@ const EnumPropertyItem rna_enum_symmetrize_direction_items[] = {
 
 #  include "DEG_depsgraph.h"
 
-#  include "ED_gpencil.h"
+#  include "ED_gpencil_legacy.h"
 #  include "ED_paint.h"
 #  include "ED_particle.h"
 
diff --git a/source/blender/makesrna/intern/rna_space.c b/source/blender/makesrna/intern/rna_space.c
index b4c1058969c..a475ccf55ba 100644
--- a/source/blender/makesrna/intern/rna_space.c
+++ b/source/blender/makesrna/intern/rna_space.c
@@ -8004,6 +8004,11 @@ static void rna_def_spreadsheet_row_filter(BlenderRNA *brna)
   RNA_def_property_ui_text(prop, "8-Bit Integer Value", "");
   RNA_def_property_update(prop, NC_SPACE | ND_SPACE_SPREADSHEET, NULL);
 
+  prop = RNA_def_property(srna, "value_int2", PROP_INT, PROP_NONE);
+  RNA_def_property_array(prop, 2);
+  RNA_def_property_ui_text(prop, "2D Vector Value", "");
+  RNA_def_property_update(prop, NC_SPACE | ND_SPACE_SPREADSHEET, NULL);
+
   prop = RNA_def_property(srna, "value_boolean", PROP_BOOLEAN, PROP_NONE);
   RNA_def_property_boolean_sdna(prop, NULL, "flag", SPREADSHEET_ROW_FILTER_BOOL_VALUE);
   RNA_def_property_ui_text(prop, "Boolean Value", "");
diff --git a/source/blender/nodes/geometry/nodes/node_geo_extrude_mesh.cc b/source/blender/nodes/geometry/nodes/node_geo_extrude_mesh.cc
index 16384125f58..8a28908afa4 100644
--- a/source/blender/nodes/geometry/nodes/node_geo_extrude_mesh.cc
+++ b/source/blender/nodes/geometry/nodes/node_geo_extrude_mesh.cc
@@ -94,25 +94,46 @@ static void expand_mesh(Mesh &mesh,
                         const int poly_expand,
                         const int loop_expand)
 {
+  /* Remove types that aren't supported for interpolation in this node. */
   if (vert_expand != 0) {
+    CustomData_free_layers(&mesh.vdata, CD_ORCO, mesh.totvert);
+    CustomData_free_layers(&mesh.vdata, CD_BWEIGHT, mesh.totvert);
+    CustomData_free_layers(&mesh.vdata, CD_SHAPEKEY, mesh.totvert);
+    CustomData_free_layers(&mesh.vdata, CD_CLOTH_ORCO, mesh.totvert);
+    CustomData_free_layers(&mesh.vdata, CD_MVERT_SKIN, mesh.totvert);
     const int old_verts_num = mesh.totvert;
     mesh.totvert += vert_expand;
     CustomData_realloc(&mesh.vdata, old_verts_num, mesh.totvert);
   }
   if (edge_expand != 0) {
+    CustomData_free_layers(&mesh.edata, CD_BWEIGHT, mesh.totedge);
+    CustomData_free_layers(&mesh.edata, CD_FREESTYLE_EDGE, mesh.totedge);
     const int old_edges_num = mesh.totedge;
     mesh.totedge += edge_expand;
     CustomData_realloc(&mesh.edata, old_edges_num, mesh.totedge);
   }
   if (poly_expand != 0) {
+    CustomData_free_layers(&mesh.pdata, CD_FACEMAP, mesh.totpoly);
+    CustomData_free_layers(&mesh.pdata, CD_FREESTYLE_FACE, mesh.totpoly);
     const int old_polys_num = mesh.totpoly;
     mesh.totpoly += poly_expand;
     CustomData_realloc(&mesh.pdata, old_polys_num, mesh.totpoly);
-    mesh.poly_offset_indices = static_cast<int *>(
-        MEM_reallocN(mesh.poly_offset_indices, sizeof(int) * (mesh.totpoly + 1)));
-    mesh.poly_offsets_for_write().last() = mesh.totloop + loop_expand;
+    implicit_sharing::resize_trivial_array(&mesh.poly_offset_indices,
+                                           &mesh.runtime->poly_offsets_sharing_info,
+                                           old_polys_num == 0 ? 0 : (old_polys_num + 1),
+                                           mesh.totpoly + 1);
+    /* Set common values for convenience. */
+    mesh.poly_offset_indices[0] = 0;
+    mesh.poly_offset_indices[mesh.totpoly] = mesh.totloop + loop_expand;
   }
   if (loop_expand != 0) {
+    CustomData_free_layers(&mesh.ldata, CD_NORMAL, mesh.totloop);
+    CustomData_free_layers(&mesh.ldata, CD_MDISPS, mesh.totloop);
+    CustomData_free_layers(&mesh.ldata, CD_TANGENT, mesh.totloop);
+    CustomData_free_layers(&mesh.ldata, CD_PAINT_MASK, mesh.totloop);
+    CustomData_free_layers(&mesh.ldata, CD_MLOOPTANGENT, mesh.totloop);
+    CustomData_free_layers(&mesh.ldata, CD_GRID_PAINT_MASK, mesh.totloop);
+    CustomData_free_layers(&mesh.ldata, CD_CUSTOMLOOPNORMAL, mesh.totloop);
     const int old_loops_num = mesh.totloop;
     mesh.totloop += loop_expand;
     CustomData_realloc(&mesh.ldata, old_loops_num, mesh.totloop);
diff --git a/source/blender/python/intern/bpy_rna_id_collection.c b/source/blender/python/intern/bpy_rna_id_collection.c
index 766c74c0bbc..df3c687307b 100644
--- a/source/blender/python/intern/bpy_rna_id_collection.c
+++ b/source/blender/python/intern/bpy_rna_id_collection.c
@@ -85,7 +85,7 @@ static int foreach_libblock_id_user_map_callback(LibraryIDLinkCallbackData *cb_d
       return IDWALK_RET_NOP;
     }
 
-    if (cb_flag & IDWALK_CB_EMBEDDED) {
+    if (cb_flag & (IDWALK_CB_EMBEDDED | IDWALK_CB_EMBEDDED_NOT_OWNING)) {
       /* We skip private pointers themselves, like root node trees, we'll 'link' their own ID
        * pointers to their 'ID owner' instead. */
       return IDWALK_RET_NOP;
diff --git a/source/blender/windowmanager/intern/wm_init_exit.cc b/source/blender/windowmanager/intern/wm_init_exit.cc
index 57b07579291..852a9f1a7ce 100644
--- a/source/blender/windowmanager/intern/wm_init_exit.cc
+++ b/source/blender/windowmanager/intern/wm_init_exit.cc
@@ -95,7 +95,7 @@
 #include "ED_anim_api.h"
 #include "ED_armature.h"
 #include "ED_asset.h"
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_keyframes_edit.h"
 #include "ED_keyframing.h"
 #include "ED_node.h"
diff --git a/source/blender/windowmanager/intern/wm_operators.c b/source/blender/windowmanager/intern/wm_operators.c
index 38cbd7d782d..548ee1440c9 100644
--- a/source/blender/windowmanager/intern/wm_operators.c
+++ b/source/blender/windowmanager/intern/wm_operators.c
@@ -73,7 +73,7 @@
 #include "IMB_imbuf_types.h"
 
 #include "ED_fileselect.h"
-#include "ED_gpencil.h"
+#include "ED_gpencil_legacy.h"
 #include "ED_numinput.h"
 #include "ED_screen.h"
 #include "ED_undo.h"
@@ -3462,7 +3462,7 @@ static int previews_id_ensure_callback(LibraryIDLinkCallbackData *cb_data)
 {
   const int cb_flag = cb_data->cb_flag;
 
-  if (cb_flag & IDWALK_CB_EMBEDDED) {
+  if (cb_flag & (IDWALK_CB_EMBEDDED | IDWALK_CB_EMBEDDED_NOT_OWNING)) {
     return IDWALK_RET_NOP;
   }
 
diff --git a/tests/python/bl_blendfile_liblink.py b/tests/python/bl_blendfile_liblink.py
index 0199132b0b9..4ee77745a90 100644
--- a/tests/python/bl_blendfile_liblink.py
+++ b/tests/python/bl_blendfile_liblink.py
@@ -220,7 +220,7 @@ class TestBlendLibLinkIndirect(TestBlendLibLinkHelper):
         assert mesh.use_fake_user is False
         assert mesh.users == 0
         # IDs explicitely linked by the user are forcefully considered directly linked.
-        assert mesh.is_library_indirect == False
+        assert mesh.is_library_indirect is False
 
         ob = bpy.data.objects.new("LocalMesh", mesh)
         coll = bpy.data.collections.new("LocalMesh")
@@ -230,19 +230,19 @@ class TestBlendLibLinkIndirect(TestBlendLibLinkHelper):
         assert material.users == 2
         assert material.is_library_indirect
         assert mesh.users == 1
-        assert mesh.is_library_indirect == False
+        assert mesh.is_library_indirect is False
 
         ob.material_slots[0].link = 'OBJECT'
         ob.material_slots[0].material = material
 
         assert material.users == 3
-        assert material.is_library_indirect == False
+        assert material.is_library_indirect is False
 
         ob.material_slots[0].material = None
 
         assert material.users == 2
         # This is not properly updated whene removing a local user of linked data.
-        assert material.is_library_indirect == False
+        assert material.is_library_indirect is False
 
         output_work_path = os.path.join(output_dir, self.unique_blendfile_name("blendfile"))
         bpy.ops.wm.save_as_mainfile(filepath=output_work_path, check_existing=False, compress=False)
@@ -270,7 +270,7 @@ class TestBlendLibLinkIndirect(TestBlendLibLinkHelper):
         assert mesh.library is not None
         assert mesh.use_fake_user is False
         assert mesh.users == 1
-        assert mesh.is_library_indirect == False
+        assert mesh.is_library_indirect is False
 
 
 class TestBlendLibAppendBasic(TestBlendLibLinkHelper):
@@ -598,7 +598,7 @@ class TestBlendLibDataLibrariesLoadLibOverride(TestBlendLibDataLibrariesLoad):
 
         # Only explicitely linked data gets a liboverride, without any handling of hierarchy/dependencies.
         assert bpy.data.collections[0].library is None
-        assert bpy.data.collections[0].is_runtime_data == False
+        assert bpy.data.collections[0].is_runtime_data is False
         assert bpy.data.collections[0].override_library is not None
         assert bpy.data.collections[0].override_library.reference == bpy.data.collections[-1]
 
@@ -616,7 +616,7 @@ class TestBlendLibDataLibrariesLoadLibOverride(TestBlendLibDataLibrariesLoad):
 
         # Only explicitely linked data gets a liboverride, without any handling of hierarchy/dependencies.
         assert bpy.data.collections[1].library is None
-        assert bpy.data.collections[1].is_runtime_data == False
+        assert bpy.data.collections[1].is_runtime_data is False
         assert bpy.data.collections[1].override_library is not None
         assert bpy.data.collections[1].override_library.reference == bpy.data.collections[-1]
 
@@ -634,7 +634,7 @@ class TestBlendLibDataLibrariesLoadLibOverride(TestBlendLibDataLibrariesLoad):
 
         # Only explicitely linked data gets a liboverride, without any handling of hierarchy/dependencies.
         assert bpy.data.collections[1].library is None
-        assert bpy.data.collections[1].is_runtime_data == False
+        assert bpy.data.collections[1].is_runtime_data is False
         assert bpy.data.collections[1].override_library is not None
         assert bpy.data.collections[1].override_library.reference == bpy.data.collections[-1]
 
@@ -699,7 +699,7 @@ class TestBlendLibDataLibrariesLoadLibOverride(TestBlendLibDataLibrariesLoad):
 
         # Only explicitely linked data gets a liboverride, without any handling of hierarchy/dependencies.
         assert bpy.data.collections[1].library is None
-        assert bpy.data.collections[1].is_runtime_data == False
+        assert bpy.data.collections[1].is_runtime_data is False
         assert bpy.data.collections[1].override_library is not None
         assert bpy.data.collections[1].override_library.reference == bpy.data.collections[-1]
 
diff --git a/tools/utils/gitea_inactive_developers.py b/tools/utils/gitea_inactive_developers.py
new file mode 100755
index 00000000000..a90cd7ececc
--- /dev/null
+++ b/tools/utils/gitea_inactive_developers.py
@@ -0,0 +1,248 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+# Script to get all the inactive gitea developers
+# Usage: GITEA_API_TOKEN=<yourtoken> python3 gitea_inactive_developers.py
+#
+# The API Token have the "read:org" or "admin:org" scope.
+#
+# Potential errors:
+# * 403 Client Error: That means the token doesn't have the right scope.
+# * 500 Server Error: The token is invalid.
+
+import csv
+import logging
+import os
+import requests
+import sys
+import yarl
+from retry import retry as retry_decorator
+import datetime
+import dataclasses as dc
+import iso8601
+
+from typing import (
+    cast,
+    Callable,
+    Dict,
+    Iterable,
+    List,
+    NewType,
+    Optional,
+    Tuple,
+    Type,
+    TypeVar,
+)
+
+logger = logging.getLogger(__file__)
+
+
+@dc.dataclass
+class TeamMember():
+    id: int
+    login: str
+    full_name: str
+    last_login: datetime.datetime
+
+    def __str__(self):
+        return "{id};{login};{full_name};{last_login};{url}\n".format(
+            id=self.id,
+            login=self.login,
+            full_name=self.full_name,
+            last_login=self.last_login,
+            url=gitea_domain + self.login,
+        )
+
+
+Page = NewType('Page', int)
+
+F = TypeVar('F', bound=Callable[..., object])
+T = TypeVar('T', bound=object)
+
+retry: Callable[[F], F] = retry_decorator(
+    tries=10, delay=1, backoff=2, logger=logger)
+
+
+def assert_cast(typ: Type[T], obj: object) -> T:
+    assert isinstance(obj, typ), f'object is not of type {typ}: {obj}'
+    return cast(T, obj)
+
+
+def get_date_object(date_string: str) -> datetime.datetime:
+    return iso8601.parse_date(date_string)
+
+
+results_per_page = 25
+
+
+def get_next_page(headers: Dict, page: int) -> int:
+    """
+    Parse the header looking for reference to next.
+    """
+    total_count = int(assert_cast(str, headers.get('X-Total-Count')))
+    next_page = page + 1 if page else 1
+
+    if next_page * results_per_page > total_count:
+        return None
+
+    return next_page
+
+
+@retry
+def fetch_single(
+    api_url: yarl.URL,
+    api_token: str,
+    method: str,
+    data: Dict[str, str],
+    page: Optional[Page] = None,
+) -> Tuple[List[object], Optional[Page]]:
+    """Generic function to query a single item from the API.
+
+    Returns:
+        A dictionary containing the item data.
+    """
+    headers = {
+        'accept': 'application/json',
+        'Authorization': 'token ' + api_token,
+    }
+
+    params = {
+        'limit': results_per_page,
+        **data,
+    }
+
+    if page is not None:
+        params['page'] = page
+
+    logger.info(f"Calling {method} ({params=}).")
+    response = requests.get(str(api_url / method), params=params, headers=headers)
+    response.raise_for_status()
+    response_json = response.json()
+
+    next_page = get_next_page(response.headers, page)
+    return response_json, None if next_page is None else Page(next_page)
+
+
+def fetch_all(
+    api_url: yarl.URL,
+    api_token: str,
+    method: str,
+    data: Dict[str, str],
+) -> Iterable[object]:
+    """Generic function to query lists from API.
+
+    Yields:
+        response_data - the result of fetch_single()
+    """
+    response_data, page = fetch_single(api_url, api_token, method, data)
+    yield from response_data if response_data is not None else ()
+    while page is not None:
+        response_data, page = fetch_single(
+            api_url, api_token, method, data, page=page)
+        yield from response_data
+
+
+def fetch_team_members(
+    api_url: yarl.URL,
+    api_token: str,
+    organization_name: str,
+    team_name: str,
+) -> List[TeamMember]:
+    """Query API for all the members of a team.
+
+    Yields:
+        TeamMember objects.
+    """
+
+    method = "orgs/{org}/teams".format(org=organization_name)
+    team_id = None
+
+    for team in cast(
+        Iterable[Dict[object, object]],
+        fetch_all(
+            api_url,
+            api_token,
+            method,
+            data={},
+        ),
+    ):
+        if team.get('name') != team_name:
+            continue
+
+        team_id = team.get('id')
+        break
+
+    if team_id is None:
+        logger.error('No team found with name: ' + team_name)
+        sys.exit(2)
+
+    method = "teams/{id}/members".format(id=team_id)
+    users = list()
+
+    for member in cast(
+        Iterable[Dict[object, object]],
+        fetch_all(
+            api_url,
+            api_token,
+            method,
+            data={},
+        ),
+    ):
+        users.append(
+            TeamMember(
+                id=assert_cast(int, member.get('id')),
+                login=assert_cast(str, member.get('login')),
+                full_name=assert_cast(str, member.get('full_name')),
+                last_login=get_date_object(
+                    assert_cast(str, member.get('last_login'))),
+            ))
+
+    return users
+
+
+def is_inactive(member: TeamMember) -> bool:
+    """
+    Returns whether the member is no longer active.
+
+    Users are active when they logged in the past 2 years.
+    """
+    tzinfo = member.last_login.tzinfo
+    two_years_ago = datetime.datetime.now(tzinfo) - datetime.timedelta(days=2 * 365)
+    return member.last_login < two_years_ago
+
+
+teams = (
+    "Developers",
+    "Add-ons",
+    "Translation",
+    "Documentation",
+    "Technical-Artists",
+    "Contributors",
+)
+
+
+api_token = os.environ['GITEA_API_TOKEN']
+gitea_domain = "https://projects.blender.org/"
+api_url = yarl.URL(gitea_domain + 'api/v1/')
+organization_name = "blender"
+
+
+def main():
+    for team_name in teams:
+        logger.warning(team_name)
+        members = fetch_team_members(
+            api_url, api_token, organization_name, team_name)
+
+        inactive_members = [str(m) for m in members if is_inactive(m)]
+
+        logger.warning("  Total members:" + str(len(members)))
+        logger.warning("  Inactive members: " + str(len(inactive_members)))
+
+        file_name = team_name.lower() + ".csv"
+        with open(file_name, 'w', newline='') as csv_file:
+            csv_file.write("id;login;full_name;last_login;url\n")
+            csv_file.writelines(inactive_members)
+        logger.warning("  Output file: " + file_name)
+
+
+if __name__ == "__main__":
+    main()