Hi all, It is about the class load/unload logic. I'm trying to remove BooleanPreferenceView. But this class is registered as a preference view : --------------- BooleanPreferenceView class>>initialize PreferenceViewRegistry ofBooleanPreferences register: self. --------------- BooleanPreferenceView also implements #unload which unregisters itself from the registry: --------------- BooleanPreferenceView class>>unload PreferenceViewRegistry ofBooleanPreferences unregister: self --------------- So ok, if I remove the class from the browser, #unload is sent and the PreferenceViewRegistry registry is kept clean. The same if I load a change set. But if I make a SLICE and load it from a fresh image, then, it seems that #unload is not sent because AnObsoleteBooleanPreferenceView is still referenced by the PreferenceViewRegistry registry. Have I missed something ? Thanks Alain