Comment 2 for bug 1437751

StacktraceTop:
 g_type_check_instance_is_fundamentally_a (type_instance=type_instance@entry=0x12d1a50, fundamental_type=fundamental_type@entry=80) at /build/buildd/glib2.0-2.43.92/./gobject/gtype.c:4028
 g_object_ref (_object=_object@entry=0x12d1a50) at /build/buildd/glib2.0-2.43.92/./gobject/gobject.c:3040
 on_partition_delete_tool_button_clicked (button=<optimized out>, user_data=<optimized out>) at gduwindow.c:3524
 _g_closure_invoke_va (closure=0x12d1a50, closure@entry=0x11c4b80, return_value=0x50, return_value@entry=0x0, instance=0x12cd100, instance@entry=0x13ca2c0, args=0x124bfa0, args@entry=0x7fff0ee18a88, n_params=46, param_types=0x3) at /build/buildd/glib2.0-2.43.92/./gobject/gclosure.c:831
 g_signal_emit_valist (instance=0x13ca2c0, signal_id=<optimized out>, detail=0, var_args=0x7fff0ee18a88) at /build/buildd/glib2.0-2.43.92/./gobject/gsignal.c:3214