I found the cause - I created the #buttonBad accessing methods with code (re)factoring (generate accessors), and in this case the accessors are made in this fashion:
CustomerSatisfaction >> buttonBad: *anObject *buttonBad := *anObject *It's better to use CustomerSatisfaction >> buttonBad: *aComposablePresenterClass *buttonBad := *aComposablePresenterClass *as this method is doing: ComposablePresenter >> instantiate: aComposablePresenterClass "Instantiate a ComposablePresenter subclass and set its instance owner" ^ aComposablePresenterClass owner: self To find the cause, I used the debugger extensively and found the core logic in ECInstVarTypeGuesser >> perform method - it was quite an exercise! Best wishes, Tomaz -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html