[gtk+] Avoid warnings with tooltips on toplevels

[Matthias Clasen <matthiasc src gnome org>]

commit dcdb00adb4be64768583eb3f0d301a931d7694d4
Author: Matthias Clasen <mclasen redhat com>
Date:   Thu Aug 5 00:12:41 2010 -0400

    Avoid warnings with tooltips on toplevels
    
    This was reported for tooltips on statusicons in bug 625235, but
    it was affecting regular toplevel windows as well.

 gtk/gtktooltip.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtktooltip.c b/gtk/gtktooltip.c
index 3a50fc0..c75f251 100644
--- a/gtk/gtktooltip.c
+++ b/gtk/gtktooltip.c
@@ -876,6 +876,8 @@ get_bounding_box (GtkWidget    *widget,
   gint x4, y4;
 
   window = gtk_widget_get_parent_window (widget);
+  if (window == NULL)
+    window = gtk_widget_get_window (widget);
 
   x = widget->allocation.x;
   y = widget->allocation.y;