JPopupMenu goes behind main JFrame after checking/unchecking its Items.

Question

I've written the following stand-alone code, which basically contains a JFrame that includes a combination of JPopupMenu's and JMenu's. If user right-clicks on the JFrame, a JPopupMenu will popup, which contains a JMenu. This JMenu also includes another JPopupMenu that contains 4 JCheckBoxMenuItems.
The problem that I'm facing is that, after I select one JCheckBoxMenuItem, the popup menu containing them, will go behind the JFrame. How can I get it to stay in front? Here's my SSCCE. I need to turn this in at work by tomorrow at the latest. So, if anyone has time, your help will be very much appreciated. Thanks!
import java.awt.Color;
import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JButton;
import javax.swing.JCheckBoxMenuItem;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JPopupMenu;
import javax.swing.SwingUtilities;
public class MyPopupTest {
      * @param args
     public MyPopupTest(){}
     public void generateMenu()
          final JFrame frame = new JFrame("My Frame");
          frame.setSize(300,300);
          final JPopupMenu popupMenu = new JPopupMenu();
          final JMenu menu = new JMenu("My Menu");
          final JPopupMenu itemsPopupMenu = new JPopupMenu();
          final JButton okButton = new JButton("OK");
          final JCheckBoxMenuItem item1 = new JCheckBoxMenuItem("Item 1", true);
          final JCheckBoxMenuItem item2 = new JCheckBoxMenuItem("Item 2", false);
          final JCheckBoxMenuItem item3 = new JCheckBoxMenuItem("Item 3", true);
          final JCheckBoxMenuItem item4 = new JCheckBoxMenuItem("Item 4", false);
          itemsPopupMenu.add(item1);
          itemsPopupMenu.add(item2);
          itemsPopupMenu.add(item3);
          itemsPopupMenu.add(item4);
          itemsPopupMenu.add(okButton);
          menu.add(itemsPopupMenu);
          popupMenu.add(menu);
          frame.addMouseListener(new MouseAdapter()
               public void mouseClicked(MouseEvent e)
                    if(SwingUtilities.isRightMouseButton(e))
                         frame.getContentPane().add(popupMenu);
                         popupMenu.setLocation(e.getPoint().x+50,e.getPoint().y);
                         popupMenu.setVisible(true);
          popupMenu.addMouseListener(new MouseAdapter()
               public void mouseEntered(MouseEvent e)
                    itemsPopupMenu.setLocation(new Point(popupMenu.getWidth()+menu.getLocationOnScreen().x, menu.getLocationOnScreen().y));
                    itemsPopupMenu.setVisible(true);
          item1.addMouseListener(new MouseAdapter()
               public void mousePressed(MouseEvent e)
                    popupMenu.setVisible(true);
               public void mouseEntered(MouseEvent e)
                    item1.setBackground(Color.PINK);
               public void mouseExited(MouseEvent e)
                    item1.setBackground(popupMenu.getBackground());
          item2.addMouseListener(new MouseAdapter()
               public void mousePressed(MouseEvent e)
                    popupMenu.setVisible(true);
               public void mouseEntered(MouseEvent e)
                    item2.setBackground(Color.PINK);
               public void mouseExited(MouseEvent e)
                    item2.setBackground(popupMenu.getBackground());
          item3.addMouseListener(new MouseAdapter()
               public void mousePressed(MouseEvent e)
                    popupMenu.setVisible(true);
               public void mouseEntered(MouseEvent e)
                    item3.setBackground(Color.PINK);
               public void mouseExited(MouseEvent e)
                    item3.setBackground(popupMenu.getBackground());
          item4.addMouseListener(new MouseAdapter()
               public void mousePressed(MouseEvent e)
                    popupMenu.setVisible(true);
               public void mouseEntered(MouseEvent e)
                    item4.setBackground(Color.PINK);
               public void mouseExited(MouseEvent e)
                    item4.setBackground(popupMenu.getBackground());
          okButton.addMouseListener(new MouseAdapter()
               public void mousePressed(MouseEvent e)
                    popupMenu.setVisible(false);
                    itemsPopupMenu.setVisible(false);
          frame.setVisible(true);
     public static void main(String [] args)
          MyPopupTest test  = new MyPopupTest();
          test.generateMenu();
}

Answer 1

Quit multi-posting. This is your third posting on this topic. Others have no idea what has already been suggested in the other postings and are wasting their time reading the posting. Keep the discussion in a single posting.
In fact I already explained to you how you can prevent the popup menu from closing and gave you a simple example to work from. For those of you that are curious. If you add a JCheckBox to a JPopupMenu, instead of a JCheckBoxMenuItem, the popup will stay open.
I can't explain the behaviour of the posted code, but when you have a smiple working solution maybe its time to use it as the basis of your solution.