Problem with JMenus that Persist - Is this a Java bug?

Question

I am having a problem with JMenus that persist. By this I mean
that my drop down menus persist on the screen even after they have
been selected.
I've checked the Java bug database, and the following seems
to come closest to my problem:
Bug ID: 4235188
JPopupMenus and JMenus persist when their JFrame becomes visible
State: Closed, not a bug
http://developer.java.sun.com/developer/bugParade/bugs/4235188.html
This page says that the matter is closed and is not a bug. The
resolution of this matter printed at the bottom of the page
is completely abstruse to me and I would appreciate any
comments to understand what they are talking about.
The code at the end of my message illustrates my problem.
1. Why should paintComponent() make any difference to
Menu behavior?
2. Is this a bug?
3. What's the workaround if I have to paint() or repaint()?
Thanks
Tony Lin
// Example of Menu Persistence Problem
// Try running this with line 41, paintComponent(), and without line 41
// Menus behave normally if line 41 is commented out
// If line 41 exists, menus will persist after they have been selected
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class P2 extends JPanel {
JMenuItem[] mi;
public P2() {
JFrame thisFrame = new JFrame();
thisFrame.getContentPane().add(this);
JMenu menu = new JMenu("My Menu");
JMenuBar mb = new JMenuBar();
mi = new JMenuItem[4];
for (int i=0; i<mi.length; i++) {
mi[i] = new JMenuItem("Menu Item " + String.valueOf(i));
menu.add(mi);
mb.add(menu);
thisFrame.setJMenuBar(mb);
thisFrame.setSize(400,200);
thisFrame.setLocation(150,200);
thisFrame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent we) {
System.exit(0);
thisFrame.setVisible(true);
public void paintComponent(Graphics g) {} //Affects menu behavior!
public static void main(String[] args) {
new P2();

Answer 1

Well, my understanding of the way painting works is that a component doesn't UNPAINT itself. Instead a message is sent to the component under the coordinates of the menu to REPAINT itself.
In your demo program the JFrame is the component under the JMenu. The paintComponent() method of JFrame is empty, so nothing gets repainted.
I added super.paintComponent(g); to the method and everything works fine.