Comment 2 for bug 844244

StacktraceTop:
 g_type_check_instance_is_a (type_instance=0x9b160a8, iface_type=158836024) at /build/buildd/glib2.0-2.29.90/./gobject/gtype.c:3943
 gtk_widget_get_mapped (widget=0x9b160a8) at /build/buildd/gtk+3.0-3.1.18/./gtk/gtkwidget.c:7461
 _gtk_widget_list_devices (widget=0x9b160a8) at /build/buildd/gtk+3.0-3.1.18/./gtk/gtkwidget.c:10994
 gtk_grab_notify_foreach (child=0x9b160a8, data=0xbf6ba394) at /build/buildd/gtk+3.0-3.1.18/./gtk/gtkmain.c:2123
 gtk_box_forall (container=0x9ae4b98, include_internals=1, callback=0x344f30 <gtk_grab_notify_foreach>, callback_data=0xbf6ba394) at /build/buildd/gtk+3.0-3.1.18/./gtk/gtkbox.c:1844