private void grab(BaseObject obj, int x, int y) {
    synchronized (grabList) {
      obj.selectAction(true);

      if (grabList.contains(obj)) {
        return;
      }

      grabList.add(obj);
      obj.setGrabbedAnchorAt(x, y);

      notifyListener(obj);
      lastGrabbed = obj;
    }
  }