return null;
JTree tree = new JTree(tl);
tree.expandRow(0);
for (int i = tree.getRowCount(); i-- > 0;)
tree.expandRow(i);
tree.setRootVisible(false);
tree.setToggleClickCount(3);
new JOptionPaneClickHandler().install(tree);
tree.getSelectionModel().setSelectionMode(
TreeSelectionModel.SINGLE_TREE_SELECTION);