Comment 11 for bug 1294741

After taking another look at lifecycle.txt, it seems like this is an use-after-free, or more like double-free thing, but in the meantime some object-related memory location was reused by another gtk object. gtk_object_destroy sets some gtk-related pointer to NULL, while gtk_label_init sets it to -1, and this is what the second sp_guideline_destroy sees.