[gtk/gtk-4-6] gtk-demo: Small fixup to the cursors demo

[Matthias Clasen <matthiasc src gnome org>]

commit 93921f32bdd9add849080ddb0f6613536fac58dc
Author: Matthias Clasen <mclasen redhat com>
Date:   Sat Dec 4 22:16:01 2021 -0500

    gtk-demo: Small fixup to the cursors demo

 demos/gtk-demo/cursors.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)
---
diff --git a/demos/gtk-demo/cursors.c b/demos/gtk-demo/cursors.c
index d1ea0314e5..31d935d813 100644
--- a/demos/gtk-demo/cursors.c
+++ b/demos/gtk-demo/cursors.c
@@ -24,6 +24,7 @@ do_cursors (GtkWidget *do_widget)
 
       builder = gtk_builder_new_from_resource ("/cursors/cursors.ui");
       window = GTK_WIDGET (gtk_builder_get_object (builder, "window"));
+      g_object_add_weak_pointer (G_OBJECT (window), (gpointer *)&window);
       gtk_window_set_display (GTK_WINDOW (window),
                               gtk_widget_get_display (do_widget));
       g_signal_connect (window, "destroy",
@@ -34,9 +35,7 @@ do_cursors (GtkWidget *do_widget)
   if (!gtk_widget_get_visible (window))
     gtk_widget_show (window);
   else
-    {
-      gtk_window_destroy (GTK_WINDOW (window));
-    }
+    gtk_window_destroy (GTK_WINDOW (window));
 
   return window;
 }