double-buffered image not refreshed while offscreen

FULL PRODUCT VERSION :
java version "1.6.0-beta2"
Java(TM) SE Runtime Environment (build 1.6.0-beta2-b85)
Java HotSpot(TM) Client VM (build 1.6.0-beta2-b85, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Linux myhostname 2.6.12-10-686 #1 Fri Apr 28 13:21:56 UTC 2006 i686 GNU/Linux


EXTRA RELEVANT SYSTEM CONFIGURATION :
I've only tested this under Linux; I don't know if it happens under other operating systems.

A DESCRIPTION OF THE PROBLEM :
The new double buffering feature in Mustang is nice, but it doesn't quite seem to be working 100% correctly. When a window is hidden and redisplayed, you get an image immediately rather than a gray rectangle, which is definitely an improvement. But if the display gets updated while hidden, the immediate image shown is that of the last displayed image, rather than the new, updated image. After a split second (about the same amount of time as the gray rectangle used to show), the updated image is displayed. This can look a bit strange, as it makes it appear that the program state has just changed right as you are viewing the window, rather than the program state having changed while the window was not visible.


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1) Run the SwingSet2 demo:
  java -jar $JAVA_HOME/demo/jfc/SwingSet2/SwingSet2.jar

2) Go to the ProgressBar demo.

3) Start loading text.

4) Minimize the SwingSet window (or switch to another desktop, or otherwise get the SwingSet window off the screen). Note how far the text has gotten in the display window at the moment when it goes offscreen.

5) Wait for about a minute for the text to finish loading.

6) Restore the window, or switch back to the desktop. Watch the image in the window closely as it appears on screen.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
I would expect that, while the window was offscreen, that the rest of the text would have loaded, been rendered, and loaded into the new doublebuffering system. Thus when the window comes into view, it should immediately show the full text of the demo, with the progress bar showing completion.
ACTUAL -
What actually happens is that the very first image displayed is identical to the last image that was shown before the window was hidden. So for a moment, you see just the beginning of the demo text, with the progress bar still only partially complete. After a split-second, the image is updated to the complete demo text and 100% complete progress bar. This gives the user the incorrect impression that the text loading just completed at that moment, rather than it having finished loading while the window was offscreen.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
/*
  * @(#)ProgressBarDemo.java 1.12 05/11/17
  *
  * Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  * -Redistribution of source code must retain the above copyright notice, this
  * list of conditions and the following disclaimer.
  *
  * -Redistribution in binary form must reproduce the above copyright notice,
  * this list of conditions and the following disclaimer in the documentation
  * and/or other materials provided with the distribution.
  *
  * Neither the name of Sun Microsystems, Inc. or the names of contributors may
  * be used to endorse or promote products derived from this software without
  * specific prior written permission.
  *
  * This software is provided "AS IS," without a warranty of any kind. ALL
  * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
  * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
  * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
  * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
  * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
  * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
  * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
  * INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
  * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
  * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
  *
  * You acknowledge that this software is not designed, licensed or intended
  * for use in the design, construction, operation or maintenance of any
  * nuclear facility.
  */
  
 /*
  * @(#)ProgressBarDemo.java 1.12 05/11/17
  */
  
  
 import javax.swing.*;
 import javax.swing.event.*;
 import javax.swing.text.*;
 import javax.swing.border.*;
 import javax.swing.colorchooser.*;
 import javax.swing.filechooser.*;
 import javax.accessibility.*;
  
 import java.awt.*;
 import java.awt.event.*;
 import java.beans.*;
 import java.util.*;
 import java.io.*;
 import java.applet.*;
 import java.net.*;
  
 /**
  * JProgressBar Demo
  *
  * @version 1.12 11/17/05
  * @author Jeff Dinkins
  # @author Peter Korn (accessibility support)
  */
 public class ProgressBarDemo extends DemoModule {
  
     /**
      * main method allows us to run as a standalone demo.
      */
     public static void main(String[] args) {
  ProgressBarDemo demo = new ProgressBarDemo(null);
  demo.mainImpl();
     }
  
     /**
      * ProgressBarDemo Constructor
      */
     public ProgressBarDemo(SwingSet2 swingset) {
  // Set the title for this demo, and an icon used to represent this
  // demo inside the SwingSet2 app.
  super(swingset, "ProgressBarDemo", "toolbar/JProgressBar.gif");
  
  createProgressPanel();
     }
  
     javax.swing.Timer timer = new javax.swing.Timer(18, createTextLoadAction());
     Action loadAction;
     Action stopAction;
     JProgressBar progressBar;
     JTextArea progressTextArea;
  
     void updateDragEnabled(boolean dragEnabled) {
         progressTextArea.setDragEnabled(dragEnabled);
     }
      
     public void createProgressPanel() {
  getDemoPanel().setLayout(new BorderLayout());
  
  JPanel textWrapper = new JPanel(new BorderLayout());
  textWrapper.setBorder(new SoftBevelBorder(BevelBorder.LOWERED));
  textWrapper.setAlignmentX(LEFT_ALIGNMENT);
  progressTextArea = new MyTextArea();
          
  progressTextArea.getAccessibleContext().setAccessibleName(getString("ProgressBarDemo.accessible_text_area_name"));
  progressTextArea.getAccessibleContext().setAccessibleName(getString("ProgressBarDemo.accessible_text_area_description"));
  textWrapper.add(new JScrollPane(progressTextArea), BorderLayout.CENTER);
  
  getDemoPanel().add(textWrapper, BorderLayout.CENTER);
  
  JPanel progressPanel = new JPanel();
  getDemoPanel().add(progressPanel, BorderLayout.SOUTH);
  
  progressBar = new JProgressBar(JProgressBar.HORIZONTAL, 0, text.length()) {
  public Dimension getPreferredSize() {
  return new Dimension(300, super.getPreferredSize().height);
  }
  };
  progressBar.getAccessibleContext().setAccessibleName(getString("ProgressBarDemo.accessible_text_loading_progress"));
  
  progressPanel.add(progressBar);
  progressPanel.add(createLoadButton());
  progressPanel.add(createStopButton());
     }
  
     public JButton createLoadButton() {
  loadAction = new AbstractAction(getString("ProgressBarDemo.start_button")) {
  public void actionPerformed(ActionEvent e) {
  loadAction.setEnabled(false);
  stopAction.setEnabled(true);
                 if (progressBar.getValue() == progressBar.getMaximum()) {
                     progressBar.setValue(0);
                     textLocation = 0;
                     progressTextArea.setText("");
                 }
  timer.start();
  }
  };
  return createButton(loadAction);
     }
  
     public JButton createStopButton() {
  stopAction = new AbstractAction(getString("ProgressBarDemo.stop_button")) {
  public void actionPerformed(ActionEvent e) {
  timer.stop();
  loadAction.setEnabled(true);
  stopAction.setEnabled(false);
  }
  };
  return createButton(stopAction);
     }
  
     public JButton createButton(Action a) {
  JButton b = new JButton();
  // setting the following client property informs the button to show
  // the action text as it's name. The default is to not show the
  // action text.
  b.putClientProperty("displayActionText", Boolean.TRUE);
  b.setAction(a);
  return b;
     }
  
  
     int textLocation = 0;
  
     String text = getString("ProgressBarDemo.text");
  
     public Action createTextLoadAction() {
  return new AbstractAction("text load action") {
  public void actionPerformed (ActionEvent e) {
  if(progressBar.getValue() < progressBar.getMaximum()) {
  progressBar.setValue(progressBar.getValue() + 1);
  progressTextArea.append(text.substring(textLocation, textLocation+1));
  textLocation++;
  } else {
  timer.stop();
  loadAction.setEnabled(true);
  stopAction.setEnabled(false);
  }
  }
  };
     }
  
  
     class MyTextArea extends JTextArea {
         public MyTextArea() {
             super(null, 0, 0);
  setEditable(false);
  setText("");
         }
  
         public float getAlignmentX () {
             return LEFT_ALIGNMENT;
         }
   
         public float getAlignmentY () {
             return TOP_ALIGNMENT;
         }
     }
 }
  
  
 
---------- END SOURCE ----------