source/blender/editors/include/UI_interface.h

@@ -896,6 +896,7 @@ void UI_but_dragflag_enable(uiBut *but, int flag);
 void UI_but_dragflag_disable(uiBut *but, int flag);
 
 void UI_but_disable(uiBut *but, const char *disabled_hint);
+void UI_but_inactive(uiBut *but, const char *disabled_hint);
 
 void UI_but_type_set_menu_from_pulldown(uiBut *but);
 

source/blender/editors/interface/interface.cc

@@ -4715,6 +4715,10 @@ static uiBut *ui_def_but_rna(uiBlock *block,
     UI_but_disable(but, info);
   }
 
+  if (but->rnapoin.data && RNA_property_is_inactive_info(&but->rnapoin, prop, &info)) {
+    UI_but_inactive(but, info);
+  }
+
   if (proptype == PROP_POINTER) {
     /* If the button shows an ID, automatically set it as focused in context so operators can
      * access it. */
@@ -5904,6 +5908,16 @@ void UI_but_dragflag_disable(uiBut *but, int flag)
   but->dragflag &= ~flag;
 }
 
+void UI_but_inactive(uiBut *but, const char *inactive_hint)
+{
+  /* Only one inactive hint at a time currently. Don't override the previous one here. */
+  if (but->disabled_info && but->disabled_info[0]) {
+    return;
+  }
+
+  but->disabled_info = inactive_hint;
+}
+
 void UI_but_disable(uiBut *but, const char *disabled_hint)
 {
   UI_but_flag_enable(but, UI_BUT_DISABLED);

source/blender/makesrna/RNA_access.h

@@ -274,6 +274,7 @@ bool RNA_property_editable(PointerRNA *ptr, PropertyRNA *prop);
  * that can be exposed in UI.
  */
 bool RNA_property_editable_info(PointerRNA *ptr, PropertyRNA *prop, const char **r_info);
+bool RNA_property_is_inactive_info(PointerRNA *ptr, PropertyRNA *prop, const char **r_info);
 /**
  * Same as RNA_property_editable(), except this checks individual items in an array.
  */

source/blender/makesrna/RNA_types.h

@@ -187,6 +187,15 @@ typedef enum PropertyFlag {
    * for pointers and collections.
    */
   PROP_EDITABLE = (1 << 0),
+  /**
+   * Inactive specifically only refers to the front end
+   * where UI elements are grayed out but can still be
+   * toggled. It is specifically used to add Disabled
+   * message for when UI is set to inactive through Python
+   * script. It is completely unrelated to anything that
+   * is performed in the backend.
+   */
+  PROP_INACTIVE = (1 << 9),
   /**
    * This property is editable even if it is lib linked,
    * meaning it will get lost on reload, but it's useful

source/blender/makesrna/intern/rna_access.cc

@@ -1935,6 +1935,32 @@ int RNA_property_ui_icon(const PropertyRNA *prop)
   return rna_ensure_property((PropertyRNA *)prop)->icon;
 }
 
+static bool rna_property_is_inactive_do(PointerRNA *ptr,
+                                     PropertyRNA *prop_orig,
+                                     const int index,
+                                     const char **r_info)
+{
+  PropertyRNA *prop = rna_ensure_property(prop_orig);
+
+  const char *info = "";
+  const int flag = (prop->itemeditable != nullptr && index >= 0) ?
+                       prop->itemeditable(ptr, index) :
+                       (prop->editable != nullptr ? prop->editable(ptr, &info) : prop->flag);
+  if (r_info != nullptr) {
+    *r_info = info;
+  }
+
+  /* Return true if the property itself is inative. */
+  if ((flag & PROP_INACTIVE) != 0) {
+    if (r_info != nullptr && (*r_info)[0] == '\0') {
+      *r_info = N_("This property is for internal use only and can't be edited");
+    }
+    return true;
+  }
+
+  return false;
+}
+
 static bool rna_property_editable_do(PointerRNA *ptr,
                                      PropertyRNA *prop_orig,
                                      const int index,
@@ -2001,6 +2027,11 @@ bool RNA_property_editable(PointerRNA *ptr, PropertyRNA *prop)
   return rna_property_editable_do(ptr, prop, -1, nullptr);
 }
 
+bool RNA_property_is_inactive_info(PointerRNA *ptr, PropertyRNA *prop, const char **r_info)
+{
+  return rna_property_is_inactive_do(ptr, prop, -1, r_info);
+}
+
 bool RNA_property_editable_info(PointerRNA *ptr, PropertyRNA *prop, const char **r_info)
 {
   return rna_property_editable_do(ptr, prop, -1, r_info);