SWT已经提供了对部分平台（比如window）上的系统托盘的支持。但支持得还不够好，我最近需要在一个聊天工具实现Balloon效果(粘附于系统托盘上的一个消息气泡效果，在IM软件中普遍被支持)，查一下SWT API,到目前为上并没有提供支持。但一个好消息是在月底交要出来的3.2M6中，将对部分API做调整，增加对Balloon的支持。
Milestone Plan
3.2
M6 March
31
,
2006
Implement custom draw
for
table and tree
Implement
native
drag source effects
for
cursor
Implement ImageTransfer support
Implement Balloon tooltips
Implement Accessibility on Mac OS X
这儿是EclipseZone上的一个针对这一效果的文章：TrayIcons and ToolTips
http://www.eclipsezone.com/eclipse/forums/t66093.rhtml甚至在官方网站上，已经提供了这一个API的Snippet
//http://dev.eclipse.org/viewcvs/index.cgi/%7Echeckout%7E/org.eclipse.swt.snippets/src/org/eclipse/swt/snippets/Snippet225.java
/** *//*******************************************************************************
* Copyright (c) 2000, 2006 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.swt.snippets;
/**//*
* Tooltip example snippet: create a balloon tooltip for a tray item
*
* For a list of all SWT example snippets see
* http://www.eclipse.org/swt/snippets/
*
* @since 3.0
*/
import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.widgets.*;
public class Snippet225 
{
public static void main(String[] args) {
Display display = new Display();
Shell shell = new Shell(display);
Image image = null;
final ToolTip tip = new ToolTip(shell, SWT.BALLOON | SWT.ICON_INFORMATION);
tip.setMessage("Here is message for the user. When the message is too long it wraps. I should say something cool but nothing comes to my mind.");
Tray tray = display.getSystemTray();
if (tray != null) {
TrayItem item = new TrayItem(tray, SWT.NONE);
image = new Image(display, Snippet225.class.getResourceAsStream("eclipse.png"));
item.setImage(image);
tip.setText("Notification from a tray item");
item.setToolTip(tip);
} else {
tip.setText("Notification from anywhere");
tip.setLocation(400, 400);
}
Button button = new Button (shell, SWT.PUSH);
button.setText("Press for balloon tip");
button.addListener(SWT.Selection, new Listener() {
public void handleEvent(Event event) {
tip.setVisible(true);
}
});
button.pack();
shell.setBounds(50, 50, 300, 200);
shell.open();
while (!shell.isDisposed()) {
if (!display.readAndDispatch()) display.sleep();
}
if (image != null) image.dispose();
display.dispose();
}
}
除此之外，也有其它的第三方API实现了此一效果。是由www.novocode.com提供的BalloonWindow。其API可在上述的网站中获得。