class TreeModelSupport {

    public void fireNewRoot() {

        Object root = treeModel.getRoot();

        /*
         * Undocumented. I think it is the only reasonable/possible solution to
         * use use null as path if there is no root. TreeModels without root
         * aren't important anyway, since JTree doesn't support them (yet).
         */
        TreePath path = (root != null) ? new TreePath(root) : null;
        fireTreeStructureChanged(path);
    }

    public  TreeModelSupport(TreeModel model);

}