Internal Frames in Java Swing

hi

I was learning Swing and I tried the following example from a book.

// File 1
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class Test2 extends Frame implements ActionListener {
   JButton openButton;
   JLayeredPane desktop;
   JInternalFrame internalFrame;
   public Test2() {
      super("Internal Frame Test");
      setSize(500,400);
      openButton = new JButton("Open");
      Panel p = new Panel();
      p.add(openButton);
      add(p, BorderLayout.SOUTH);
      addWindowListener(new BasicWindowMonitor());
      openButton.addActionListener(this);
      desktop = new JDesktopPane();
      desktop.setOpaque(true);
      add(desktop, BorderLayout.CENTER);
}
public void actionPerformed(ActionEvent e) {
   System.out.println("TEST1");
   if ((internalFrame == null) || (internalFrame.isClosed())) {
      try {
         internalFrame = new JInternalFrame("Internal Frame",false,false,false, true);
         internalFrame.setBounds(50, 50, 200, 100);
         desktop.add(internalFrame, new Integer(1));
      }
   catch(Exception xxx)
   {
      System.out.println("Exception"+xxx);
   }
   System.out.println("TEST");
   }
}
public static void main(String args[]) {
   Test2 sif = new Test2();
   sif.setVisible(true);
}
}


// File 2
import java.awt.event.*;
import java.awt.Window;

public class BasicWindowMonitor extends WindowAdapter {
     public void windowClosing(WindowEvent e) {
          Window w = e.getWindow();
          w.setVisible(false);
          w.dispose();
          System.exit(0);
     }  
}

The files are compiled and executed successfully.
As written in the program when I clicke the "Open" button it should open an internal frame but it is not opening any internal frames.

I have j2sdk1.4.2 and JRE 1.4.2 installed
Processor AMD Athelon XP
OS Windows XP

Any idea about this??