Comment 2 for bug 811401

StacktraceTop:
 g_type_check_instance_cast (type_instance=0x92870d8, iface_type=153927760) at /build/buildd/glib2.0-2.29.10/./gobject/gtype.c:3977
 gtk_image_menu_item_forall (container=0x92870d8, include_internals=1, callback=0xb74b0c30 <gtk_grab_notify_foreach>, callback_data=0xbf212274) at /build/buildd/gtk+3.0-3.1.8/./gtk/gtkimagemenuitem.c:634
 gtk_container_forall (container=0x92870d8, callback=0xb74b0c30 <gtk_grab_notify_foreach>, callback_data=0xbf212274) at /build/buildd/gtk+3.0-3.1.8/./gtk/gtkcontainer.c:2031
 gtk_grab_notify_foreach (child=0x92870d8, data=0xbf212274) at /build/buildd/gtk+3.0-3.1.8/./gtk/gtkmain.c:2099
 gtk_menu_shell_forall (container=0x92cb088, include_internals=1, callback=0xb74b0c30 <gtk_grab_notify_foreach>, callback_data=0xbf212274) at /build/buildd/gtk+3.0-3.1.8/./gtk/gtkmenushell.c:1248