setDefaultButton-焦点损失

Question

I have found that when a modal JDialog launches a second modal JDialog, and when that second JDialog is disposed, the first JDialog seems to (mostly) ignore the keyboard.

I have included a sample program to demonstrate the issue. On running the code, I should be able to hit the space bar (the button in the main JFrame has focus) and the first JDialog is launched, containing a button (also with focus).

I hit the space bar and the second JDialog is launched. Hitting enter, the second JDialog disposes.

Hitting space bar on the first JDialog results in no response. Alt- F4 will close the first JDialog, so the keyboard is not completely disconnected.

Repeating the above procedure using the mouse only, the issue does not occur.

The background to all of this is I wanted to set the default button on a dialog (in which the user enters some text and other data). If I comment out the setDefaultButton in the second JDialog and now use TAB to move around, the issue does not occur.

In short, I want to be able to set a default button on a JDialog (so I can hit the enter key), but at the same time, I want default focus on a JTextField.

I am on Ubuntu 13.10 using the OpenJDK (64 bit). I have found this happens regardless of using the GTK+ look and feel or the metal look and feel (that is, not setting any look and feel).

I cannot reproduce on Windows XP (using Oracle Java 32 bit).

On reading a few posts, it seems Linux and Java have a few focus problems and so I'm not sure if this is a programming error on my part or I've stumbled upon a Linux/Java issue.

Any ideas please?

Below is example code which reproduces the issue.

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.WindowConstants;


public class Test extends JFrame
{
    public Test()
    {
        JButton button = new JButton( "Test" );
        button.addActionListener( new ActionListener() { public void actionPerformed( ActionEvent actionEvent ) { new Test1( Test.this ); } } );

        JPanel panel = new JPanel();
        panel.add( button );

        getContentPane().add( panel  );
        pack();
        setDefaultCloseOperation( WindowConstants.DISPOSE_ON_CLOSE );
        setVisible( true );
    }


    protected class Test1 extends JDialog
    {
        public Test1( JFrame owner )
        {
            super( owner );

            JButton button = new JButton( "1" );
            button.addActionListener( new ActionListener() { public void actionPerformed( ActionEvent actionEvent ) { new Test2( Test1.this ); } } );

            JPanel panel = new JPanel();
            panel.add( button );

            getContentPane().add( panel  );
            pack();
            setDefaultCloseOperation( WindowConstants.DISPOSE_ON_CLOSE );
            setLocationRelativeTo( null );
            setModalityType( ModalityType.APPLICATION_MODAL );
            setVisible( true ); 
        }
    }


    protected class Test2 extends JDialog
    {
        public Test2( JDialog owner )
        {
            super( owner );

            JTextField textField = new JTextField();

            JButton button = new JButton( "2" );
            getRootPane().setDefaultButton( button );
            button.addActionListener
            (
                new ActionListener()
                {
                    public void actionPerformed( ActionEvent actionEvent )
                    { 
//                      Test2.this.getRootPane().setDefaultButton( null ); // Makes no difference!
                        Test2.this.dispose();
                    }
                } 
            );

            JPanel panel = new JPanel( new BorderLayout() );
            panel.add( textField, BorderLayout.CENTER );
            panel.add( button, BorderLayout.SOUTH );

            getContentPane().add( panel  );
            pack();
            setDefaultCloseOperation( WindowConstants.DISPOSE_ON_CLOSE );
            setLocationRelativeTo( null );
            setModalityType( ModalityType.APPLICATION_MODAL );
            setVisible( true );
        }
    }


    public static void main( String[] args )
    {
        new Test();
    }
}