code: function onActivateEvent() {
           // register pointer events
           me.input.registerPointerEvent("pointerdown", this, this.clicked.bind(this));
           me.input.registerPointerEvent("pointerup", this, this.release.bind(this));
           me.input.registerPointerEvent("pointercancel", this, this.release.bind(this));
           me.input.registerPointerEvent("pointerenter", this, this.enter.bind(this));
           me.input.registerPointerEvent("pointerleave", this, this.leave.bind(this));
         }
docs: function called when added to the game world or a container
  @ignore