3 files changed, 50 insertions, 4 deletions
diff --git a/source/blender/editors/include/ED_screen.h b/source/blender/editors/include/ED_screen.h
index 08b6c02a8d0..ef3ff7874df 100644
--- a/source/blender/editors/include/ED_screen.h
+++ b/source/blender/editors/include/ED_screen.h
@@ -439,6 +439,7 @@ bool ED_region_panel_category_gutter_calc_rect(const ARegion *region, rcti *r_re
 bool ED_region_panel_category_gutter_isect_xy(const ARegion *region, const int event_xy[2]);
 
 bool ED_region_contains_xy(const struct ARegion *region, const int event_xy[2]);
+ARegion *ED_area_find_region_xy_visual(const ScrArea *area, int regiontype, const int event_xy[2]);
 
 /* interface_region_hud.c */
 struct ARegionType *ED_area_type_hud(int space_type);
diff --git a/source/blender/editors/interface/interface_dropboxes.cc b/source/blender/editors/interface/interface_dropboxes.cc
index 81a1354cbe7..369efa7c52e 100644
--- a/source/blender/editors/interface/interface_dropboxes.cc
+++ b/source/blender/editors/interface/interface_dropboxes.cc
@@ -39,12 +39,12 @@ static bool ui_tree_view_drop_poll(bContext *C, wmDrag *drag, const wmEvent *eve
     return false;
   }
 
-  if (drag->free_disabled_info) {
-    MEM_SAFE_FREE(drag->disabled_info);
+  if (drag->drop_state.free_disabled_info) {
+    MEM_SAFE_FREE(drag->drop_state.disabled_info);
   }
 
-  drag->free_disabled_info = false;
-  return UI_tree_view_item_can_drop(hovered_tree_item, drag, &drag->disabled_info);
+  drag->drop_state.free_disabled_info = false;
+  return UI_tree_view_item_can_drop(hovered_tree_item, drag, &drag->drop_state.disabled_info);
 }
 
 static char *ui_tree_view_drop_tooltip(bContext *C,
diff --git a/source/blender/editors/screen/area_query.c b/source/blender/editors/screen/area_query.c
index fd4f3964398..30e744ca174 100644
--- a/source/blender/editors/screen/area_query.c
+++ b/source/blender/editors/screen/area_query.c
@@ -140,6 +140,10 @@ bool ED_region_overlap_isect_xy_with_margin(const ARegion *region,
           ED_region_overlap_isect_y_with_margin(region, event_xy[1], margin));
 }
 
+/**
+ * \note: This may return true for multiple overlapping regions. If it matters, check overlapped
+ *        regions first (#ARegion.overlap).
+ */
 bool ED_region_contains_xy(const ARegion *region, const int event_xy[2])
 {
   /* Only use the margin when inside the region. */
@@ -188,3 +192,44 @@ bool ED_region_contains_xy(const ARegion *region, const int event_xy[2])
   }
   return false;
 }
+
+/**
+ * Similar to #BKE_area_find_region_xy() but when \a event_xy intersects an overlapping region,
+ * this returns the region that is visually under the cursor. E.g. when over the
+ * transparent part of the region, it returns the region underneath.
+ *
+ * The overlapping region is determined using the #ED_region_contains_xy() query.
+ */
+ARegion *ED_area_find_region_xy_visual(const ScrArea *area,
+                                       const int regiontype,
+                                       const int event_xy[2])
+{
+  if (!area) {
+    return NULL;
+  }
+
+  /* Check overlapped regions first. */
+  LISTBASE_FOREACH (ARegion *, region, &area->regionbase) {
+    if (!region->overlap) {
+      continue;
+    }
+    if (ELEM(regiontype, RGN_TYPE_ANY, region->regiontype)) {
+      if (ED_region_contains_xy(region, event_xy)) {
+        return region;
+      }
+    }
+  }
+  /* Now non-overlapping ones. */
+  LISTBASE_FOREACH (ARegion *, region, &area->regionbase) {
+    if (region->overlap) {
+      continue;
+    }
+    if (ELEM(regiontype, RGN_TYPE_ANY, region->regiontype)) {
+      if (ED_region_contains_xy(region, event_xy)) {
+        return region;
+      }
+    }
+  }
+
+  return NULL;
+}