public Gtk.Window GetToplevel (object sender)
{
Widget wsender = sender as Widget;
Gtk.Window toplevel = null;
if (wsender != null && !(wsender is MenuItem))
toplevel = (Gtk.Window)wsender.Toplevel;
else if (fsview != null)
toplevel = fsview;
else
toplevel = main_window;
return toplevel;
}