Fix T79275: Missing redraw for pinned active tool settings panels

In the 3D view sidebar, the active tool settings panel can be pinned to other
categories, and in those other categories it doesn't redraw when the active
tool changes. This commit checks for pinned panels from the "Tool" category
when checking whether to redraw.

Note that the relatively expensive string comparison is only done for
currently visible pinned panels.

Differential Revision: https://developer.blender.org/D9012

source/blender/editors/include/UI_interface.h

@@ -1685,6 +1685,7 @@ struct Panel *UI_panel_begin(struct ARegion *region,
                              bool *r_open);
 void UI_panel_end(const struct ARegion *region, uiBlock *block, int width, int height, bool open);
 
+bool UI_panel_is_active(const struct Panel *panel);
 void UI_panel_label_offset(struct uiBlock *block, int *r_x, int *r_y);
 int UI_panel_size_y(const struct Panel *panel);
 bool UI_panel_is_dragging(const struct Panel *panel);

source/blender/editors/interface/interface_panel.c

@@ -877,6 +877,11 @@ void UI_panels_set_expansion_from_seach_filter(const bContext *C, ARegion *regio
   }
 }
 
+bool UI_panel_is_active(const Panel *panel)
+{
+  return panel->runtime_flag & PANEL_ACTIVE;
+}
+
 /** \} */
 
 /* -------------------------------------------------------------------- */

source/blender/editors/screen/area.c

@@ -450,8 +450,25 @@ void ED_area_do_mgs_subscribe_for_tool_ui(
     struct wmMsgBus *mbus)
 {
   BLI_assert(region->regiontype == RGN_TYPE_UI);
+  const char *panel_category_tool = "Tool";
   const char *category = UI_panel_category_active_get(region, false);
-  if (category && STREQ(category, "Tool")) {
+
+  bool update_region = false;
+  if (category && STREQ(category, panel_category_tool)) {
+    update_region = true;
+  }
+  else {
+    /* Check if a tool category panel is pinned and visible in another category. */
+    LISTBASE_FOREACH (Panel *, panel, &region->panels) {
+      if (UI_panel_is_active(panel) && panel->flag & PNL_PIN &&
+          STREQ(panel->type->category, panel_category_tool)) {
+        update_region = true;
+        break;
+      }
+    }
+  }
+
+  if (update_region) {
     wmMsgSubscribeValue msg_sub_value_region_tag_redraw = {
         .owner = region,
         .user_data = region,