FULL PRODUCT VERSION :
java version "1.6.0-rc"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.6.0-rc-b71)
Java HotSpot(TM) 64-Bit Server VM (build 1.6.0-rc-b71, mixed mode)


ADDITIONAL OS VERSION INFORMATION :
Linux helium 2.6.12-10-amd64-generic #1 Mon Jan 16 17:16:24 UTC 2006 x86_64 GNU/Linux
Windows XP


A DESCRIPTION OF THE PROBLEM :
All the native "tray icons" on my Ubuntu system perform their action when I single-click on them. A Java TrayIcon, though, doesn't respond until I double-click.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Compile and run the test case.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Single-clicking on the tray icon should say "ouch!".
ACTUAL -
I have to double-click before I see "ouch!".

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import javax.swing.*;

public class SystemTrayTest {
        private TrayIcon trayIcon;
        private BufferedImage image;

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

        public SystemTrayTest() {
                if (SystemTray.isSupported()) {
                        SystemTray tray = SystemTray.getSystemTray();
                        Dimension size = tray.getTrayIconSize();
                        image = new BufferedImage(size.width, size.height, BufferedImage.TYPE_INT_RGB);
                        ActionListener listener = new ActionListener() {
                                public void actionPerformed(ActionEvent e) {
                                        System.out.println("Ouch!");
                                }
                        };
                        trayIcon = new TrayIcon(image, "test");
                        trayIcon.addActionListener(listener);
                        try {
                                tray.add(trayIcon);
                        } catch (AWTException ex) {
                                ex.printStackTrace();
                        }
                        Timer timer = new Timer(50, new ActionListener() {
                                public void actionPerformed(ActionEvent e) {
                                        updateImage();
                                }
                        });
                        timer.start();
                } else {
                        System.out.println("no system tray!");
                }
        }

        int i = 0;

        private void updateImage() {
                Graphics2D g = image.createGraphics();
                g.setColor(new Color(i, i, i));
                i = (i + 1) % 256;
                g.fillRect(0, 0, image.getWidth(), image.getHeight());
                trayIcon.setImage(image);
                trayIcon.setToolTip("Value: " + i);
        }
}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
If you add a MouseListener instead, you can use mouseClicked to perform an action on single click, but to avoid Java applications feeling non-native, the ActionListener behavior should be fixed.