Extending JPanel to contain a JRootPane - problems with scroll panes

Question

I am trying to write a JPanel subclass that contains a JRootPane, similar to the way that JFrame contains a JRootPane. The reason that I am doing this is that I would like to be able to intercept mouse events using the JGlassPane facility, but adding the glasspane to the JFrame is problematic since it then intercepts mouse events over all components in the JFrame, including the menu bar. It seems simpler to me to have the JRootPane owned by a JPanel, to give me better control over intercepting events. I've got an implementation working with the JFrame case, but have had to handle many small "gotchas", and at least one more exists. I'm hoping to simplify things by moving away from this way of doing things.
I wrote a straightforward RootPanePanel class that extends JPanel and implements RootPaneContainer, delegating all of the add methods to the JRootPane's content pane. Here's the constructor for RootPanePanel:
public RootPanePanel (LayoutManager layout) {
        rootPane = new JRootPane ();
        rootPane.setOpaque(true);
        rootPane.getContentPane().setLayout(layout);
        super.add (rootPane);
}RootPanePanel also delegates calls like getContentPane/setContentPane to the JRootPane.
To test my implementation, I wrote a main method that looks like the following:
public static void main (String[] args) {
  SwingUtilities.invokeLater(new Runnable () {
    public void run () {
      try {
        JEditorPane editorPane = new JEditorPane ("http://www.archives.gov/exhibits/charters/print_friendly.html?page=declaration_transcript_content.html&title=NARA%20%7C%20The%20Declaration%20of%20Independence%3A%20A%20Transcription");
        JScrollPane scrollPane = new JScrollPane (editorPane);
        JFrame frame = new JFrame ("Test RootPanePanel");
        RootPanePanel panel = new RootPanePanel ();                    
        panel.add(scrollPane);
        frame.add(panel, BorderLayout.CENTER);
        scrollPane.setPreferredSize(new Dimension(800, 600));
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize (640, 480);
        frame.pack ();
        frame.setVisible(true);
      } catch (Exception e) {
        e.printStackTrace();
  });Note that I'm not actually using JEditorPane in my application, but it is the simplest component that displays the problem I'm encountering.
When this code runs, it is fine, as long as the JFrame is big enough to display the scrollbars for the JScrollPane. If the JFrame is made small enough, the scrollbars are not displayed.
If I instead add the JScrollPane to the JFrame directly, it behaves as you would expect.
Is this a problem of mixing heavyweight and lightweight components? It doesn't seem like it should be; in both cases the JScrollPane is handling the same client component, the JEditorPane.
Any suggestions/ideas are welcome!

Answer 1

Here's the full RootPanePanel class in case people want to try it out
import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.HeadlessException;
import java.awt.LayoutManager;
import java.io.IOException;
import javax.swing.JEditorPane;
import javax.swing.JFrame;
import javax.swing.JLayeredPane;
import javax.swing.JPanel;
import javax.swing.JRootPane;
import javax.swing.JScrollPane;
import javax.swing.RootPaneContainer;
import javax.swing.SwingUtilities;
public class RootPanePanel extends JPanel implements RootPaneContainer {
     private JRootPane rootPane;
     public RootPanePanel () {
          this (new BorderLayout());
     public RootPanePanel (LayoutManager layout) {
          rootPane = new JRootPane ();
          rootPane.setOpaque(true);
          rootPane.getContentPane().setLayout(layout);
          super.add (rootPane);
     public Container getContentPane() {
          return rootPane.getContentPane();
     public Component getGlassPane() {
          return rootPane.getGlassPane();
     public JLayeredPane getLayeredPane() {
          return rootPane.getLayeredPane();
     public void setContentPane(Container arg0) {
          rootPane.setContentPane(arg0);
     public void setGlassPane(Component arg0) {
          rootPane.setGlassPane(arg0);
     public void setLayeredPane(JLayeredPane arg0) {
          rootPane.setLayeredPane(arg0);
     @Override
     protected void addImpl(Component comp, Object constraints, int index)
          if (comp == rootPane) {
               super.addImpl(comp, constraints, index);
          else {
               getContentPane().add(comp, constraints, index);
     @Override
     public Component add(Component comp, int index) {
          return rootPane.getContentPane().add(comp, index);
     @Override
     public void add(Component comp, Object constraints, int index) {
          rootPane.getContentPane().add(comp, constraints, index);
     @Override
     public void add(Component comp, Object constraints) {
          rootPane.getContentPane().add(comp, constraints);
     @Override
     public Component add(Component comp) {
          return rootPane.getContentPane().add(comp);
     @Override
     public Component add(String name, Component comp) {
          return rootPane.getContentPane().add(name, comp);
     public static void main (String[] args) {
          SwingUtilities.invokeLater(new Runnable () {
               public void run () {
                    try {
                         JEditorPane editorPane = new JEditorPane ("http://www.archives.gov/exhibits/charters/print_friendly.html?page=declaration_transcript_content.html&title=NARA%20%7C%20The%20Declaration%20of%20Independence%3A%20A%20Transcription");
                         JScrollPane scrollPane = new JScrollPane (editorPane);
                         JFrame frame = new JFrame ("Test RootPanePanel");
                         RootPanePanel panel = new RootPanePanel ();                    
                         panel.add(scrollPane);
                         frame.add(panel, BorderLayout.CENTER);
                         scrollPane.setPreferredSize(new Dimension(800, 600));                                                                                                                                                 
                         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                         frame.setSize (640, 480);
                         frame.pack ();
                         frame.setVisible(true);                                                                                                    
                    } catch (HeadlessException e) {
                         // TODO Auto-generated catch block
                         e.printStackTrace();
                    } catch (IOException e) {
                         // TODO Auto-generated catch block
                         e.printStackTrace();
     public JRootPane getRootPane() {
          return rootPane;
}