private MouseShortcut toMouseShortcut(MouseEvent event) {
      int button = MouseShortcut.getButton(event);
      int clickCount = event instanceof MouseWheelEvent ? 1 : event.getClickCount();
      if (0 <= button && clickCount <= myClickCount) {
        int modifiers = event.getModifiersEx();
        return new MouseShortcut(button, modifiers, clickCount);
      }
      return null;
    }
private MouseShortcut toMouseShortcut(MouseEvent event)