Johan, I made a hierarchical state machine framework in VA Smalltalk, and use it to this day in an application that has several state machines comprising hundreds of states. ��Unfortunately, it's not open source, and I don't own the code, so I can't share it. ��It has #assumeState and #relinquishState methods that get sent when a state is entered or left, and #assumeSuperstate and #relinquishSuperstate methods that get sent as a state transition crosses the contours of superstates. ��If an open source equivalent exists, I'd be interested in checking it out.