static class PopupMenuHelper extends MouseAdapter {
  JPopupMenu menu;
  Point point;
  
  /** override me  */
  swappable void fillMenu() {
  }

  public void mousePressed(MouseEvent e) {
    displayMenu(e);
  }

  public void mouseReleased(MouseEvent e) {
    displayMenu(e);
  }

  private void displayMenu(MouseEvent e) {
    boolean popupTrigger = e.isPopupTrigger();
    if (popupTrigger) {
      JPopupMenu menu = new JPopupMenu();
      int count = menu.getComponentCount();
      this.menu = menu;
      this.point = e.getPoint();
      fillMenu();
      this.menu = null;
      if (menu.getComponentCount() != count)
        menu.show(e.getComponent(), e.getX(), e.getY());
    }
  }

  public void install(JComponent component) {
    component.addMouseListener(this);
  }
}