Hi adrian I think that I fixed the code and that now you can load it into pharo Then I did TraitDescription allSubInstancesDo: [ :each | each notifyUsersOfChangedSelectors: each selectors ]. TPureBehavior compileAll and I get no messages when I execute | behaviorsUsingTraits | behaviorsUsingTraits := (TraitDescription allSubInstances gather: [:each | each users]) asSet. behaviorsUsingTraits do: [ :each | each selectorsDo: [ :selector | (each >> selector) methodClass == each ifFalse: [ Transcript show: each name , '>>' , selector , ' ---methodClass: ' , (each >> selector) methodClass name ] ] ] I got one test not working.... in addition that the fileouttest. I should write some other tests. if r is an alias to foo (A>>r) selector should return r and not foo A>>r class A TB>>r class TB stef