* gtk/Widget.custom (StyleGetProperty): return null if
gtksharp_widget_style_get_property returns FALSE (property
doesn't exist) [Fixes#81445]
* gtk/glue/widget.c (gtksharp_widget_style_get_property): check
return of gtk_widget_class_find_style_property for NULL; function now
returns TRUE if spec is not NULL, FALSE otherwise
svn path=/trunk/gtk-sharp/; revision=76217