I'm going back and forth on where this code should live.  I think it's always going to be a bit controversial to "mix-in" our own `on close` handler to the view.  But I'm not sure if we should really differentiate between the context-as-a-constructor-function and context-as-an-object case.  In either case, I might argue that providing a close handler is a good idea.  I'm curious to hear your thoughts on why we should only attach this method in the constructor function case.