private void newFolder(DefaultMutableTreeNode node) {
public void newFolder() {
  private void newFolder(DefaultMutableTreeNode node) {    String name = JOptionPane.showInputDialog("New folder name");    if (name != null) {      DefaultMutableTreeNode newNode = new DefaultMutableTreeNode(name, true);      addNode(node, newNode);      workspace.setSelection(newNode);    }  }