public boolean isCellEditable(EventObject event) {
    boolean returnValue = false;
    if (event instanceof MouseEvent) {
      MouseEvent mouseEvent = (MouseEvent) event;
      TreePath path = tree.getPathForLocation(mouseEvent.getX(),
          mouseEvent.getY());
      if (path != null) {
        Object node = path.getLastPathComponent();
        if ((node != null) && (node instanceof DefaultMutableTreeNode)) {
          DefaultMutableTreeNode treeNode = (DefaultMutableTreeNode) node;
          Object userObject = treeNode.getUserObject();
          returnValue = ((treeNode.isLeaf()) && (userObject instanceof MyCheckBoxNode));
        }
      }
    }
    return returnValue;
  }