Under JDK 1.2, when displayed under OpenWindows, the included test case
will incorrectly display the buttons contained within the JPanel. The
first time it displays, it may be correct. However, if the dialog is
dismissed (either via the window manager header or by hitting the
"Quit" button), then the next time it displays, one of the buttons will
disappear to leave a light blue background in its place. On subsequent
displays, more buttons will disappear and the remaining ones will slide
down within the window. After multiple iterations of dismissing and
recreating, all of the buttons will be gone, leaving only the blue
background.

This problem will occur consistently under OpenWindows, but it
behaves correctly under CDE.

Another apparent requirement is that it only occurs on systems with
256MB or more of memory. This problem has been recreated on 4 different
systems with 256MB or greater of physical memory. Conversely, I was
not able to recreate it on several other machines with the same
OS+patches, but which had 64MB or 128MB of memory. [Obviously this
might just be a coincidence, but it seemed unlikely enough to be
worth mentioning.]

I've attached a small jpeg snapshot of 5 successive cycles of popping
up the JPanel and dismissing it, to show the shifting and eventual
disappearance of the contents.


I've recreated this with multiple JDKs, including:

    java version "1.2.2"
    Classic VM (build JDK-1.2.2-001, green threads, sunwjit)
and
    java version "java1.2"
    Solaris VM (build Solaris_JDK_1.2_01_dev05_fcsK, native threads, sunwjit)

To compile and run the test case:

    % javac Test.java
    % java Test

The test case is:

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//--------------- Test.java
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;

public class Test extends JPanel {
    private static JFrame f = null;
    private JDialog td = null;

    public Test() {
        this.setLayout(new BorderLayout());
        this.setBorder(new EmptyBorder(30,30,30,30));
        JButton jb = new JButton("click here");
        jb.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) { dofile(); }
        });
        this.add(jb, BorderLayout.CENTER);
    }

    protected void dofile() {
        if (td == null)
            td = new TDialog();
        td.show();
    }

    private class TDialog extends JDialog {
        JPanel p;
        JButton b;
        TDialog() {
            p = new JPanel(new GridLayout(4,0));
            for (int i = 0; i < 3; i++) {
                b = new JButton(String.valueOf(i));
                p.add(b);
            }
            b = new JButton("quit");
            b.addActionListener(new ActionListener() {
                public void actionPerformed(ActionEvent e) { cancel(); }
            });
            p.add(b);
            this.getContentPane().add(p);
            this.pack();
        }
        void cancel() {
            this.setVisible(false);
        }
    }

    public static void main(String argv[]) {
        f = new JFrame("Test");
        f.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) { System.exit(0); }
        });
        Test t = new Test();
        f.getContentPane().add(t);
        f.pack();

        Dimension dm = Toolkit.getDefaultToolkit().getScreenSize();
        Dimension dt = f.getSize();

        // centered on the screen to start
        f.setLocation(dm.width/2-dt.width/2, dm.height/2-dt.height/2);
        f.setVisible(true);
    }
}
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