Focus unable to traverse in the menubar

ADDITIONAL OS VERSION INFORMATION :
Windows XP SP2 32bit

A DESCRIPTION OF THE PROBLEM :
After focus moving into JMenuBar, whose focus traversal key is disabled by default, it never moves to other focusable component.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run the attached test case.
sdk/jre/bin/java FocusTraversal

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Test finished successfully and silently.
ACTUAL -
Test failed with exception.

ERROR MESSAGES/STACK TRACES THAT OCCUR :
Exception in thread "main" java.lang.Exception: Problem moving focus from javax.swing.JMenuBar
at FocusTraversal.main(FocusTraversal.java:102)

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
/*
 * Portions Copyright (c) 2011 xxxxx Corporation
 */

import java.awt.Component;
import java.awt.ContainerOrderFocusTraversalPolicy;
import java.awt.BorderLayout;
import java.awt.Robot;
import java.awt.Toolkit;
import java.awt.event.KeyEvent;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

import sun.awt.SunToolkit;

public class FocusTraversal {
    static JFrame jf = null;
    static Component owner = null;

    static final class SetupGui implements Runnable {
        public void run() {
            jf = new JFrame("Focus traversal test");
            jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

            JMenuBar mb = new JMenuBar();
            mb.add(new JMenu("menu1").add(new JMenuItem("menu_item1")));

            JButton jb1 = new JButton("button1");
            JButton jb2 = new JButton("button2");

            JPanel jp = new JPanel(new BorderLayout());
            jp.add(jb1);
            jp.add(mb, BorderLayout.NORTH);
            jp.add(jb2, BorderLayout.SOUTH);

            jf.getContentPane().add(jp);

            jf.setFocusTraversalPolicy(
                    new ContainerOrderFocusTraversalPolicy());

            jf.pack();
            jb1.requestFocusInWindow();
            jf.setVisible(true);
        }
    }

    static final class GetFocusOwner implements Runnable {
        public void run() {
            owner = jf.getFocusOwner();
        }
    }

    public static void main(String[] args) throws Exception {
        Robot robot = new Robot();
        robot.setAutoDelay(50);
        SunToolkit toolkit = (SunToolkit)Toolkit.getDefaultToolkit();
        SwingUtilities.invokeAndWait(new SetupGui());
        try {
            toolkit.realSync();

            GetFocusOwner gfo = new GetFocusOwner();
            Component last = null;
            do {
                SwingUtilities.invokeAndWait(gfo);
                if (owner == last) {
                    throw new Exception("Problem moving focus from " +
                            owner.getClass().getName());
                }
                last = owner;
                // Press the TAB key to move the focus onto the next component
                robot.keyPress(KeyEvent.VK_TAB);
                robot.keyRelease(KeyEvent.VK_TAB);
                toolkit.realSync();
            } while (owner != jf);
        } finally {
            jf.dispose();
        }
    }
}

---------- END SOURCE ----------