code: function (/* event */) {
          this.setRegion(this.unclicked_region);
          // account for the different sprite size
          this.pos.y -= this.unclicked_region.height - this.height;
          this.height = this.unclicked_region.height;
          // don't propagate the event
          return false;
      }
docs: function called when the pointer button is released