[gtk/wip/muktupavels/fix-critical-warning-master] menu: fix critical warning

[Alberts Muktupāvels <muktupavels src gnome org>]

commit cfdc6019cbdf72cc77eb90d5e512c52a5c96f315
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Thu Nov 14 18:02:36 2019 +0200

    menu: fix critical warning
    
    Unset gdk-attached-grab-window from correct surface.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/issues/1899

 gtk/gtkmenu.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)
---
diff --git a/gtk/gtkmenu.c b/gtk/gtkmenu.c
index c95036fdd1..e16916a8fe 100644
--- a/gtk/gtkmenu.c
+++ b/gtk/gtkmenu.c
@@ -2068,16 +2068,19 @@ menu_grab_transfer_surface_get (GtkMenu *menu)
 static void
 menu_grab_transfer_surface_destroy (GtkMenu *menu)
 {
+  GtkMenuPrivate *priv = menu->priv;
   GdkSurface *surface = g_object_get_data (G_OBJECT (menu), "gtk-menu-transfer-surface");
   if (surface)
     {
-      GdkSurface *widget_surface;
+      GdkSurface *toplevel_surface;
 
       gdk_surface_destroy (surface);
       g_object_set_data (G_OBJECT (menu), I_("gtk-menu-transfer-surface"), NULL);
 
-      widget_surface = gtk_native_get_surface (gtk_widget_get_native (GTK_WIDGET (menu)));
-      g_object_set_data (G_OBJECT (widget_surface), I_("gdk-attached-grab-surface"), surface);
+      toplevel_surface = gtk_native_get_surface (GTK_NATIVE (priv->toplevel));
+
+      if (toplevel_surface != NULL)
+        g_object_set_data (G_OBJECT (toplevel_surface), I_("gdk-attached-grab-surface"), NULL);
     }
 }