static <A> DefaultTreeCellRenderer customToStringTreeCellRenderer(final F1<A, S> toString) {
  ret new DefaultTreeCellRenderer {
    @Override
    public Component getTreeCellRendererComponent(
      JTree tree, O value, bool selected, bool expanded, bool leaf,
      int row, bool hasFocus) {
      ret super.getTreeCellRendererComponent(tree,
        callF(toString, ((DefaultMutableTreeNode) value).getUserObject()),
        selected, expanded, leaf, row, hasFocus);
    }
  };
}