If the event was to catch all json responses from a specific set of listeners and not all of the listeners are from that set or do not have a json response, then the event object would need to be able to inspect the currently invoked listener and decide what to do with the response. Currently each time, we'd only be able to have all of the responses in which to filter through.

I just ran into http://www.elpauer.org/stuff/a_deeper_look_at_signals_and_slots.pdf which is interesting to read