Holger Hans Peter Freyther wrote
once the package is unloaded
Browsing Announcement subclasses, I see RPackageUnregistered and CategoryRemoved. Maybe one of those would help. Also, it's better to ask user questions on pharo-users@lists.gforge.inria.fr, so your question doesn't get lost and it gives the devs inboxes a break too ;) HTH
Cheers,
Sean