Comment 2 for bug 921316

StacktraceTop:
 g_data_set_internal (dataset=0x0, new_destroy_func=0, new_data=0x0, key_id=53, datalist=0x90e910) at /build/buildd/glib2.0-2.31.12/./glib/gdataset.c:373
 g_datalist_id_set_data_full (datalist=0x90e910, key_id=53, data=0x0, destroy_func=0) at /build/buildd/glib2.0-2.31.12/./glib/gdataset.c:680
 g_object_real_dispose (object=0x90e900) at /build/buildd/glib2.0-2.31.12/./gobject/gobject.c:1001
 g_object_unref (_object=0x90e900) at /build/buildd/glib2.0-2.31.12/./gobject/gobject.c:2971
 slot_rep (dup__=0x7f6bbcba4b70 <sigc::internal::typed_slot_rep<sigc::bound_mem_functor6<void, unity::PanelMenuView, int, int, int, int, unsigned long, unsigned long> >::dup(void*)>, this=0x17c7420, destroy__=0x7f6bbcba4080 <sigc::internal::typed_slot_rep<sigc::bound_mem_functor6<void, unity::PanelMenuView, int, int, int, int, unsigned long, unsigned long> >::destroy(void*)>, call__=0x17c7420) at /usr/include/sigc++-2.0/sigc++/functors/slot_base.h:84