Hi Ben,
I've gave that a go and had some success, but it raised an architectural question I ask near the end. I've documented my investigation here in case it is of use to others new to Spec or the Spec documentation being developed.
Spec documentation is actually under heavy construction :) May I keep this content for further quotation?
So the question this leads up to is... Should child ComposableModels all reference the same WindowModel as their owner?
The thing is, the isnât var window doesnât point to the same, but the method `window` does :) Could you try something like: PhLTitledTreeModel>>repository: aRepository repositoryHolder value: aRepository. self repository whenChangedSend: #refresh to: self. "<--subscription-of-concern" self refresh. self whenBuiltDo: [ self window whenClosed: [ self repository unsubscribe: self ] ] Thanks for your investigation :) Ben