Wayland: implement scale factor windows as popups - cont'd

src/Fl_Screen_Driver.H

@@ -79,8 +79,9 @@ public:
   static const int fl_YValue;
   static const int fl_XNegative;
   static const int fl_YNegative;
-  // Used when transient scale windows are implemented as popups
+  // Next 2 are used when transient scale windows are implemented as popups
   static Fl_Window *transient_scale_parent;
+  static void del_transient_window(void *);
   // key_table and key_table_size are used in fl_shortcut to translate key names
   struct Keyname {
     unsigned int key;

src/Fl_Screen_Driver.cxx

@@ -388,8 +388,8 @@ static Fl_Window *transient_scale_window = NULL;
 Fl_Window *Fl_Screen_Driver::transient_scale_parent = NULL;
 
 
-static void del_transient_window(void *) {
-  Fl_Screen_Driver::transient_scale_parent = NULL;
+void Fl_Screen_Driver::del_transient_window(void *) {
+  transient_scale_parent = NULL;
   delete (Fl_Image*)transient_scale_window->shape();
   delete transient_scale_window;
   transient_scale_window = NULL;

src/drivers/Wayland/Fl_Wayland_Window_Driver.cxx

@@ -435,9 +435,11 @@ static void destroy_surface_caution_pointer_focus(struct wl_surface *surface,
 
 void Fl_Wayland_Window_Driver::hide() {
   if (pWindow == Fl_Screen_Driver::transient_scale_parent) {
-    // Don't hide the parent of a running transient scale window
-    // because the transient is a popup and MUST be deleted first.
-    return;
+    // Delete also the running transient scale window
+    // because the transient is a popup and MUST be deleted
+    // before its parent.
+    Fl::remove_timeout(Fl_Screen_Driver::del_transient_window);
+    Fl_Screen_Driver::del_transient_window(NULL);
   }
   Fl_X* ip = Fl_X::flx(pWindow);
   if (hide_common()) return;