7 files changed, 39 insertions, 5 deletions

diff --git a/source/blender/blenkernel/BKE_screen.h b/source/blender/blenkernel/BKE_screen.h
index 9a7d2bde810..a86953f35cc 100644
--- a/source/blender/blenkernel/BKE_screen.h
+++ b/source/blender/blenkernel/BKE_screen.h
@@ -385,6 +385,7 @@ typedef struct MenuType {
   bool (*poll)(const struct bContext *C, struct MenuType *mt);
   /* draw entirely, view changes should be handled here */
   void (*draw)(const struct bContext *C, struct Menu *menu);
+  void (*listener)(const wmRegionListenerParams *params);
 
   /* RNA integration */
   ExtensionRNA rna_ext;
diff --git a/source/blender/editors/include/UI_interface.h b/source/blender/editors/include/UI_interface.h
index b4c8ea6e5eb..1098266331f 100644
--- a/source/blender/editors/include/UI_interface.h
+++ b/source/blender/editors/include/UI_interface.h
@@ -784,6 +784,9 @@ void UI_block_set_search_only(uiBlock *block, bool search_only);
  * Can be called with C==NULL.
  */
 void UI_block_free(const struct bContext *C, uiBlock *block);
+
+void UI_block_listen(const uiBlock *block, const struct wmRegionListenerParams *listener_params);
+
 /**
  * Can be called with C==NULL.
  */
@@ -3198,9 +3201,6 @@ void UI_interface_tag_script_reload(void);
 /* Support click-drag motion which presses the button and closes a popover (like a menu). */
 #define USE_UI_POPOVER_ONCE
 
-void UI_block_views_listen(const uiBlock *block,
-                           const struct wmRegionListenerParams *listener_params);
-
 bool UI_view_item_is_active(const uiViewItemHandle *item_handle);
 bool UI_view_item_matches(const uiViewItemHandle *a_handle, const uiViewItemHandle *b_handle);
 /**
diff --git a/source/blender/editors/interface/interface.cc b/source/blender/editors/interface/interface.cc
index 1f88d25af2b..331d1581db5 100644
--- a/source/blender/editors/interface/interface.cc
+++ b/source/blender/editors/interface/interface.cc
@@ -3474,6 +3474,7 @@ void UI_block_free(const bContext *C, uiBlock *block)
 
   BLI_freelistN(&block->saferct);
   BLI_freelistN(&block->color_pickers.list);
+  BLI_freelistN(&block->dynamic_listeners);
 
   ui_block_free_button_groups(block);
   ui_block_free_views(block);
@@ -3481,6 +3482,20 @@ void UI_block_free(const bContext *C, uiBlock *block)
   MEM_freeN(block);
 }
 
+void UI_block_listen(const uiBlock *block, const wmRegionListenerParams *listener_params)
+{
+  /* Don't need to let invisible blocks (old blocks from previous redraw) listen. */
+  if (!block->active) {
+    return;
+  }
+
+  LISTBASE_FOREACH (uiBlockDynamicListener *, listener, &block->dynamic_listeners) {
+    listener->listener_func(listener_params);
+  }
+
+  ui_block_views_listen(block, listener_params);
+}
+
 void UI_blocklist_update_window_matrix(const bContext *C, const ListBase *lb)
 {
   ARegion *region = CTX_wm_region(C);
diff --git a/source/blender/editors/interface/interface_intern.h b/source/blender/editors/interface/interface_intern.h
index 6ef81ad897e..982ac1753e1 100644
--- a/source/blender/editors/interface/interface_intern.h
+++ b/source/blender/editors/interface/interface_intern.h
@@ -477,6 +477,12 @@ typedef enum uiButtonGroupFlag {
 } uiButtonGroupFlag;
 ENUM_OPERATORS(uiButtonGroupFlag, UI_BUTTON_GROUP_PANEL_HEADER);
 
+typedef struct uiBlockDynamicListener {
+  struct uiBlockDynamicListener *next, *prev;
+
+  void (*listener_func)(const struct wmRegionListenerParams *params);
+} uiBlockDynamicListener;
+
 struct uiBlock {
   uiBlock *next, *prev;
 
@@ -499,6 +505,8 @@ struct uiBlock {
    * state that is persistent over redraws (e.g. collapsed tree-view items). */
   ListBase views;
 
+  ListBase dynamic_listeners; /* #uiBlockDynamicListener */
+
   char name[UI_MAX_NAME_STR];
 
   float winmat[4][4];
@@ -1540,6 +1548,8 @@ void ui_interface_tag_script_reload_queries(void);
 /* interface_view.cc */
 
 void ui_block_free_views(struct uiBlock *block);
+void ui_block_views_listen(const uiBlock *block,
+                           const struct wmRegionListenerParams *listener_params);
 uiViewHandle *ui_block_view_find_matching_in_old_block(const uiBlock *new_block,
                                                        const uiViewHandle *new_view);
 
diff --git a/source/blender/editors/interface/interface_layout.c b/source/blender/editors/interface/interface_layout.c
index 496f72c089a..a456cef7be6 100644
--- a/source/blender/editors/interface/interface_layout.c
+++ b/source/blender/editors/interface/interface_layout.c
@@ -5814,6 +5814,14 @@ void UI_menutype_draw(bContext *C, MenuType *mt, struct uiLayout *layout)
     printf("%s: opening menu \"%s\"\n", __func__, mt->idname);
   }
 
+  if (mt->listener) {
+    /* Forward the menu type listener to the block we're drawing in. */
+    uiBlock *block = uiLayoutGetBlock(layout);
+    uiBlockDynamicListener *listener = MEM_mallocN(sizeof(*listener), "uiBlockDynamicListener");
+    listener->listener_func = mt->listener;
+    BLI_addtail(&block->dynamic_listeners, listener);
+  }
+
   if (layout->context) {
     CTX_store_set(C, layout->context);
   }
diff --git a/source/blender/editors/interface/views/interface_view.cc b/source/blender/editors/interface/views/interface_view.cc
index c568a8cab74..71974b4d2f9 100644
--- a/source/blender/editors/interface/views/interface_view.cc
+++ b/source/blender/editors/interface/views/interface_view.cc
@@ -81,7 +81,7 @@ void ui_block_free_views(uiBlock *block)
   }
 }
 
-void UI_block_views_listen(const uiBlock *block, const wmRegionListenerParams *listener_params)
+void ui_block_views_listen(const uiBlock *block, const wmRegionListenerParams *listener_params)
 {
   ARegion *region = listener_params->region;
 
diff --git a/source/blender/editors/screen/area.c b/source/blender/editors/screen/area.c
index 8db968cbb8a..a62e027ba03 100644
--- a/source/blender/editors/screen/area.c
+++ b/source/blender/editors/screen/area.c
@@ -147,7 +147,7 @@ void ED_region_do_listen(wmRegionListenerParams *params)
   }
 
   LISTBASE_FOREACH (uiBlock *, block, &region->uiblocks) {
-    UI_block_views_listen(block, params);
+    UI_block_listen(block, params);
   }
 
   LISTBASE_FOREACH (uiList *, list, &region->ui_lists) {