lib/metro/scene.rb
def notification(event,sender=nil)
      sender = sender || UnknownSender
      state.fire_events_for_notification(event,sender)
    end
def notification(event,sender=nil)
      sender = sender || UnknownSender
      state.fire_events_for_notification(event,sender)
    end
Post a custom notification event. This will trigger an event for all the
 objects that are registered for notification with the current state.