Popupmenu & JComboBox shows up behind JInternalFrame on glasspane

Question

Till Java 6 update 12 we used setLightWeightPopupEnabled on the popupmenus and JComboBoxes to make them appear on the toplevel when showing the glasspane. The situation is as followed:
- A Swing application
- Over the Swing application is a glasspane (extends JPanel)
- Added on the glasspane is a JInternalFrame (with on it components like a JPanel)
- When clicking with right mouse button, a popupmenu shows up. When using setLightWeightPopupEnabled it works perfectly
But when Java 6 update 12 was released, the popupmenu and JComboBox popup are shown behind the JInternalFrame (but above the glasspane).
SUN made some adjustments in the system. Does anyone knows how I can solve the problem as described above?

Answer 1

I made a simple code example which simulates the problem. The combobox popup falls behind the JInternalFrame. Another strange effect is when you try to resize the JInternalFrame, the JInternalFrame is closed.
import java.awt.BorderLayout;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JInternalFrame;
import javax.swing.JPanel;
public class PopupBehindInternalFrame
     public static void main (String args[]){
          JFrame frame = new JFrame();
          JPanel panel = new JPanel();
          frame.getContentPane().add(panel);
          frame.setSize(800, 600);
          frame.setVisible(true);
          JInternalFrame jif = new JInternalFrame();
          jif.setSize(400, 300);
          jif.setResizable(true);
          JPanel panelJif = new JPanel();
          jif.add(panelJif, BorderLayout.SOUTH);
          JComboBox cb = new JComboBox();
          cb.setSize(100, 10);
          cb.addItem("Test 1");
          cb.addItem("Test 2");
          cb.addItem("Test 3");
          cb.addItem("Test 4");
          cb.setLightWeightPopupEnabled(false);
          panelJif.add(cb);
          panel.getRootPane().setGlassPane(GlassPane.getInstance());
          GlassPane.getInstance().setVisible(true);
          GlassPane.getInstance().add(jif);
          jif.setVisible(true);
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.MouseAdapter;
import javax.swing.InputVerifier;
import javax.swing.JComponent;
import javax.swing.JPanel;
public class GlassPane extends JPanel
     private static final long serialVersionUID = 1L;
     private static GlassPane glassPane = null;
     private Color color = new Color(0, 128, 128, 128);
     public GlassPane()
          setOpaque(false);
          setLayout(null);
          addMouseListener(new MouseAdapter()
          setInputVerifier(new InputVerifier()
               public boolean verify(JComponent input)
                    return !isVisible();
     protected void paintComponent(Graphics g)
          if (getComponents().length > 0)
               Graphics2D g2 = (Graphics2D) g.create();
               g2.setColor(color);
               g2.fillRect(0, 0, getWidth(), getHeight());
               g2.dispose();
          else
               super.paintComponent(g);
     public static GlassPane getInstance()
          if (glassPane == null)
               glassPane = new GlassPane();
          return glassPane;
}