GdkWindow's position

[Matí­as Alejandro Torres <torresmat gmail com>]

Hi all, i'm having problems trying to get top level windows' position 
(including WM decorations).

It seems to me, that Widgets' GdkWindows are set when these are drawn. 
What i do to the position of a widget is:


gtk_widget_show_all (GTK_WIDGET (tip));

   if (!GTK_WIDGET_NO_WINDOW (GTK_WIDGET (tip)))
       gdk_window_get_root_origin (GDK_WINDOW (GTK_WIDGET 
(tip)->window), &x, &y);

gtk_widget_hide (GTK_WIDGET (tip));


gdk_window_get_root_origin throws an error If i try to call it before 
the widget is exposed:

[..] assertion `GDK_IS_WINDOW (window)' failed

Is there a way to get a widget's GdkWindow before it is drawn? 

Thanks in advance.