Fix missing redraw of asset shelves on tool changes

Context sensitivity for asset shelves is important, for example it may react to
mode or tool changes.

Initially reviewed in:
https://projects.blender.org/blender/blender/pulls/121671

Part of the brush assets project, see:
- https://projects.blender.org/blender/blender/issues/116337
- https://projects.blender.org/blender/blender/pulls/106303

source/blender/editors/asset/ED_asset_shelf.hh

@@ -23,6 +23,7 @@ struct Main;
 struct SpaceType;
 struct uiBlock;
 struct RegionPollParams;
+struct wmRegionMessageSubscribeParams;
 struct wmWindowManager;
 
 namespace blender {
@@ -52,6 +53,7 @@ void region_init(wmWindowManager *wm, ARegion *region);
 int region_snap(const ARegion *region, int size, int axis);
 void region_on_user_resize(const ARegion *region);
 void region_listen(const wmRegionListenerParams *params);
+void region_message_subscribe(const wmRegionMessageSubscribeParams *params);
 void region_layout(const bContext *C, ARegion *region);
 void region_draw(const bContext *C, ARegion *region);
 void region_on_poll_success(const bContext *C, ARegion *region);

source/blender/editors/asset/intern/asset_shelf.cc

@@ -26,6 +26,7 @@
 #include "ED_asset_list.hh"
 #include "ED_screen.hh"
 
+#include "RNA_access.hh"
 #include "RNA_prototypes.h"
 
 #include "UI_interface.hh"
@@ -34,6 +35,7 @@
 #include "UI_view2d.hh"
 
 #include "WM_api.hh"
+#include "WM_message.hh"
 
 #include "ED_asset_shelf.hh"
 #include "asset_shelf.hh"
@@ -329,6 +331,20 @@ void region_listen(const wmRegionListenerParams *params)
   }
 }
 
+void region_message_subscribe(const wmRegionMessageSubscribeParams *params)
+{
+  wmMsgBus *mbus = params->message_bus;
+  WorkSpace *workspace = params->workspace;
+  ARegion *region = params->region;
+
+  wmMsgSubscribeValue msg_sub_value_region_tag_redraw{};
+  msg_sub_value_region_tag_redraw.owner = region;
+  msg_sub_value_region_tag_redraw.user_data = region;
+  msg_sub_value_region_tag_redraw.notify = ED_region_do_msg_notify_tag_redraw;
+  WM_msg_subscribe_rna_prop(
+      mbus, &workspace->id, workspace, WorkSpace, tools, &msg_sub_value_region_tag_redraw);
+}
+
 void region_init(wmWindowManager *wm, ARegion *region)
 {
   /* Region-data should've been created by a previously called #region_on_poll_success(). */

source/blender/editors/space_image/space_image.cc

@@ -1204,6 +1204,7 @@ void ED_spacetype_image()
   art->free = asset::shelf::region_free;
   art->on_poll_success = asset::shelf::region_on_poll_success;
   art->listener = asset::shelf::region_listen;
+  art->message_subscribe = asset::shelf::region_message_subscribe;
   art->poll = asset::shelf::regions_poll;
   art->snap_size = asset::shelf::region_snap;
   art->on_user_resize = asset::shelf::region_on_user_resize;

source/blender/editors/space_view3d/space_view3d.cc

@@ -2179,6 +2179,7 @@ void ED_spacetype_view3d()
   art->free = asset::shelf::region_free;
   art->on_poll_success = asset::shelf::region_on_poll_success;
   art->listener = asset::shelf::region_listen;
+  art->message_subscribe = asset::shelf::region_message_subscribe;
   art->poll = asset::shelf::regions_poll;
   art->snap_size = asset::shelf::region_snap;
   art->on_user_resize = asset::shelf::region_on_user_resize;