Hi, if you try to follow the code that is executed when adding a method, it gets quite complex. One reason was that there where both #basicAddSelector:withMethod and #addSelectorSilently:withMethod. I have cleaned that up already. The next step is addSelector:withMethod:notifying: We never use the requestor, so the argument is a leftover from a prior cleanup (this was even much more complex!). The PR changes all code that used to be in #addSelector:withMethod:notifying: to be in #addSelector:withMethod: and fixes all senders. The method addSelector:withMethod:notifying: is deprecated, but with a auto-rewrite deprecation: existing code will just work while the sender will be refactored automatically at runtime when it does the call. (thus this will not impact backward compatibility as long as we keep that method). The PR needs a review: https://github.com/pharo-project/pharo/pull/1376 Marcus