code: function onDeactivateEvent() {
           // cancel all event subscriptions
           me.event.unsubscribe(this.vpChangeHdlr);
           me.event.unsubscribe(this.vpResizeHdlr);
           me.event.unsubscribe(this.vpLoadedHdlr);
         }
docs: called when the layer is removed from the game world or a container