How to select multiple nodes, which are not next to each other, in a tree?

Question

The following code suppose to allow user select any combination of nodes (because of DISCONTIGUOUS_TREE_SELECTION), however, I can only select nodes which are next to each other. Can some one told me how to make this DISCONTIGUOUS_TREE_SELECTION work?
Thank you very much!
import javax.swing.*;
import javax.swing.tree.*;
public class TestTree extends JFrame {
public TestTree() {
super();
setBounds(0,0,500,500);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JTree tree = new JTree();
getContentPane().add(tree);
TreeSelectionModel model = new DefaultTreeSelectionModel();
model.setSelectionMode(TreeSelectionModel.DISCONTIGUOUS_TREE_SELECTION);
tree.setSelectionModel(model);
public static void main(String [] args) {
TestTree test = new TestTree();
test.show();

Answer 1

In Windows you hold down the Ctrl key while clicking on the nodes you want to select. Don't know the equivalent in other environments.