[Pharo-project] adding traits programatically

Hi, I'm trying to add/remove traits from a class programatically and I have a problem... What I'm doing is, for instance: NSProxy traitCompostition: TNSLogConsole. and NSProxy traitComposition: TNSLogNone. (as a way to replace logging strategies)... but nothing happens... bah... in the browser the class definition is affected, but the application still works as if none changed... do I need to force a class recompilation after changing trait composition? what I'm doing wrong? Cheers, Esteban