Fix #137386: UI: Show Default Dursor in Paint Mode Menus and Dialogs

Ensure the use of the default mouse pointer cursor in paint mode
dialogs and menus by checking for temporary regions before setting
the "dot" cursor.

Pull Request: https://projects.blender.org/blender/blender/pulls/137793

source/blender/editors/sculpt_paint/paint_cursor.cc

@@ -10,6 +10,7 @@
 
 #include "MEM_guardedalloc.h"
 
+#include "BLI_listbase.h"
 #include "BLI_math_axis_angle.hh"
 #include "BLI_math_matrix.hh"
 #include "BLI_math_rotation.h"
@@ -1243,6 +1244,7 @@ struct PaintCursorContext {
   ARegion *region;
   wmWindow *win;
   wmWindowManager *wm;
+  bScreen *screen;
   Depsgraph *depsgraph;
   Scene *scene;
   UnifiedPaintSettings *ups;
@@ -1311,6 +1313,7 @@ static bool paint_cursor_context_init(bContext *C,
   pcontext.region = region;
   pcontext.wm = CTX_wm_manager(C);
   pcontext.win = CTX_wm_window(C);
+  pcontext.screen = CTX_wm_screen(C);
   pcontext.depsgraph = CTX_data_depsgraph_pointer(C);
   pcontext.scene = CTX_data_scene(C);
   pcontext.ups = &pcontext.scene->toolsettings->unified_paint_settings;
@@ -1455,6 +1458,17 @@ static void paint_update_mouse_cursor(PaintCursorContext &pcontext)
      * with the UI (dragging a number button for e.g.), see: #102792. */
     return;
   }
+
+  /* Don't set the cursor when a temporary popup is opened (e.g. a context menu, pie menu or
+   * dialog), see: #137386. */
+  if (!BLI_listbase_is_empty(&pcontext.screen->regionbase)) {
+    LISTBASE_FOREACH (ARegion *, region, &pcontext.screen->regionbase) {
+      if (region->regiontype == RGN_TYPE_TEMPORARY) {
+        return;
+      }
+    }
+  }
+
   if (ELEM(pcontext.mode, PaintMode::GPencil, PaintMode::VertexGPencil)) {
     WM_cursor_set(pcontext.win, WM_CURSOR_DOT);
   }