getRootPane() default button - Is this a bug?

问题

I have made an SSCCE. Please note that it must be Windows Look&Feel.

import java.awt.*;
import javax.swing.*;

public class DefaultButtonBug {
private static final String LAF_WINDOWS = "com.sun.java.swing.plaf.windows.WindowsLookAndFeel";

public static void main(String[] args) {

    try {
        UIManager.setLookAndFeel(LAF_WINDOWS);
    } catch (Exception ex) {
        System.out.println("Setting the L&F failed so I cannot reproduce the bug.");
        System.exit(1);
    }

    EventQueue.invokeLater(new Runnable() {

        @Override
        public void run() {
            JPanel content = new JPanel();
            JButton defaultButton = new JButton("Default");

            content.add(defaultButton);

            JFrame frame = new JFrame();

            frame.getRootPane().setDefaultButton(defaultButton);
            frame.setContentPane(content);
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.pack();
            frame.setVisible(true);                
        }
    });
}
}

Launch this
The button should be focused. If not, click it.
Click on any other window, to make sure this current window loses the focus
The button keeps animating in blue tints, even when this window has no focus anymore!

The button 'pulsing' animation is something not present in the standard Java L&F.

Remark that when this button is no longer the default button (remove the appropriate line in the code), the button will be gray after the window loses focus and there is no animation whatsoever.

My question to you is: is this considered a bug? Because this makes the EDT keep doing stuff instead of being idle when the window is hidden behind another window too (I did some profiling). Indeed, that's the stuff that bothers me the most of all: hiding the window does not make the EDT go idle.

回答1:

getRootPane() default button - Is this a bug?

not as described in a comment by @Guillaume Polet
but I'd be inclined to use KeyBindings, because any JComponents with FocusInWindow and added ActionListener can consume() ENTER key pressed, for all JButtons JComponents
focus is managable by getInputMap(JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT/*.WHEN_FOCUSED*/)
notice (Win OS) JButton has implemented TAB as an accelerator in KeyBindings, too.

from code

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;

public class DefaultButtonBug {

    private static final String LAF_WINDOWS = "com.sun.java.swing.plaf.windows.WindowsLookAndFeel";

    public static void main(String[] args) {
        try {
            UIManager.setLookAndFeel(LAF_WINDOWS);
        } catch (Exception ex) {
            System.out.println("Setting the L&F failed so I cannot reproduce the bug.");
            System.exit(1);
        }
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                JPanel content = new JPanel();
                JButton focusedButton1 = new JButton("Focused");
                focusedButton1.addActionListener(new ActionListener() {
                    @Override
                    public void actionPerformed(ActionEvent e) {
                        System.out.println("Focused pressed");
                    }
                });
                content.add(focusedButton1);
                final JButton defaultButton2 = new JButton("Default");
                defaultButton2.setIcon(UIManager.getIcon("OptionPane.informationIcon"));
                defaultButton2.addActionListener(new ActionListener() {
                    @Override
                    public void actionPerformed(ActionEvent e) {
                        System.out.println("Default pressed");
                    }
                });
                defaultButton2.getModel().addChangeListener(new ChangeListener() {
                    @Override
                    public void stateChanged(ChangeEvent e) {
                        ButtonModel model = (ButtonModel) e.getSource();
                        if (model.isRollover()) {
                            defaultButton2.setIcon(UIManager.getIcon("OptionPane.errorIcon"));
                        } else {
                            defaultButton2.setIcon(UIManager.getIcon("OptionPane.informationIcon"));
                        }
                    }
                });
                content.add(defaultButton2);
                JFrame frame = new JFrame();
                frame.getRootPane().setDefaultButton(defaultButton2);
                frame.getRootPane().getInputMap(
                        JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT/*.WHEN_FOCUSED*/)
                        .put(KeyStroke.getKeyStroke("ENTER"), "clickButton");
                frame.getRootPane().getActionMap().put("clickButton", new AbstractAction() {
                    private static final long serialVersionUID = 1L;

                    @Override
                    public void actionPerformed(ActionEvent e) {
                        defaultButton2.doClick();
                    }
                });
                frame.getRootPane().setDefaultButton(defaultButton2);
                frame.setContentPane(content);
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.pack();
                frame.setVisible(true);
            }
        });
    }
}

learning item of day

on Win7/8 (Java6/7) are allowed mouse event on un_focused Java Window (for all standard L&F), can be listener from ChangeListener added to ButtonModel
doesn't work on WinXP

focused