JDialog not showing minimize/close button

Question

When researching the problem, it seems most people are wanting to do the opposite (i.e remove the minimize/close button). I've had no success using the reoccurrent setUndecorated and setDefaultCloseOperation

Here is my code:

private class TestDialog extends JDialog 
{
    public static final String title_ = "Test Dialog";

    public TestDialog(JFrame parent)
    {
        super(parent,title_,true);
        setMinimumSize(new Dimension(500,500));
        setLocationRelativeTo(null);
        setUndecorated(false);
        setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
    }
}

When I display the dialog I get the following:

Other info:
OS: Ubuntu
Java version: 1.7.0_55

Answer 1

It's not clear where things may have gone awry, but the complete example below works on Ubuntu 12, Java 6; it may help you pin down the problem. Note that all top-level containers must be constructed on the event dispatch thread.

import java.awt.Dimension;
import java.awt.EventQueue;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.WindowConstants;


public class TestDialog extends JDialog {

    public static final String title = "Test Dialog";

    public TestDialog(JFrame parent) {
        super(parent, title, true);
        add(new JPanel(){

            @Override
            public Dimension getPreferredSize() {
                return new Dimension(320, 240);
            }
        });
        pack();
        setLocationRelativeTo(null);
        setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
    }
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                new TestDialog(null).setVisible(true);
            }
        });
    }
}

Answer 2

I have found a temporary solution of sorts, if you change the following line:

super(parent, title, true);

to

super(null, title, Dialog.ModalityType.MODELESS);

then the window close button will appear when using GNOME. I am not sure what other issues this could cause however.