[gtk/kill-register-surface: 7/10] gtk-demo: Stop using gdk_surface_get_user_data

[Matthias Clasen <matthiasc src gnome org>]

commit 9fbb6478b29c4849dbf1517f685ee1cf9661abed
Author: Matthias Clasen <mclasen redhat com>
Date:   Sat Feb 23 16:54:51 2019 -0500

    gtk-demo: Stop using gdk_surface_get_user_data
    
    Use gtk_root_get_for_surface instead.

 demos/gtk-demo/changedisplay.c | 14 +++-----------
 1 file changed, 3 insertions(+), 11 deletions(-)
---
diff --git a/demos/gtk-demo/changedisplay.c b/demos/gtk-demo/changedisplay.c
index 4c36010e7b..5f5717c43d 100644
--- a/demos/gtk-demo/changedisplay.c
+++ b/demos/gtk-demo/changedisplay.c
@@ -71,20 +71,12 @@ find_toplevel_at_pointer (GdkDisplay *display)
   GdkSurface *pointer_window;
   GtkWidget *widget = NULL;
 
-  pointer_window = gdk_device_get_surface_at_position (gtk_get_current_event_device (),
-                                                      NULL, NULL);
+  pointer_window = gdk_device_get_surface_at_position (gtk_get_current_event_device (), NULL, NULL);
 
-  /* The user data field of a GdkSurface is used to store a pointer
-   * to the widget that created it.
-   */
   if (pointer_window)
-    {
-      gpointer widget_ptr;
-      gdk_surface_get_user_data (pointer_window, &widget_ptr);
-      widget = widget_ptr;
-    }
+    widget = GTK_WIDGET (gtk_root_get_for_surface (pointer_window));
 
-  return widget ? gtk_widget_get_toplevel (widget) : NULL;
+  return widget;
 }
 
 static void