Create Your Own Window System on the NetBeans Window System

One big reason for using the NetBeans Platform is its out-of-the-box window system. However, maybe you like the concept of a window system, but not how it is implemented in the NetBeans Platform? Not to worry. You can create your own window system on top of the NetBeans Platform's Window System API, which means you'll have a custom window system that still integrates with all of the other NetBeans idioms, via ExplorerManager to explorer views (e.g., BeanTreeView) and Nodes.

Eppleton, the Munich-based NetBeans Platform consultancy, has been learning about this area of the NetBeans Platform recently, for one of its customers. The end result was the integration of the SwingX project's "org.jdesktop.swingx.JXPanel", together with "javax.swing.JLayeredPane", to create the translucent effects of the TopComponents in the screenshot below:

I.e., your TopComponents could be JXPanels, if that's the way you'd prefer them to be. Or something else.

In the image above, there are in fact 3 TopComponents, one of which has this client property in its constructor:

// setting this property informs the Windowmanager that this window is
// our Main Window. Not a standard property.
putClientProperty(TranslucentWindowManager.MAINWINDOW, Boolean.TRUE);

But how to get started with all of this? There's a "DummyWindowManager" in the NetBeans sources that you can start experimenting with. Let's do so now.


  1. In your application, remove core-windows.jar, i.e., you do not want the "Core - Windows" module to be installed in your application, since you'll be providing your own window system.

    A simple way to remove that JAR is to go to "" in your application and use this list of disabled modules (definitely won't work in all cases, since your dependencies will be different depending on what else you're using, but if you're starting from scratch, this will be all you'll need):


    Note the line in bold below, i.e., that's the line that will result in the "core-windows.jar" to be excluded.


  2. Now add this class to a module in your application:

    Especially note this class-level annotation, which results in your window manager replacing the one provided by the NetBeans Platform:

    @ServiceProvider(service = WindowManager.class, supersedes = "")

    In other words, when the module has been built, you'll find a META-INF/services registration consisting of these entries:


    Note: Make sure to add the required NetBeans API modules to the application (i.e., Nodes API, Window System API, and Utilities API).


  3. Somehow you now need to open your TopComponents into your new window system. Normally the opening of the TopComponents would be handled by core-windows.jar, which you have now excluded. So now you need to open them manually, i.e., yourself. For example, in a ModuleInstall class, add this code:
    public void restored() {
        WindowManager.getDefault().invokeWhenUIReady(new Runnable() {
            public void run() {


  4. When you run the application, you'll see this result:

Now look more closely at and change it to fit your business requirements.


If you omit from your app, then there is no need to supersede

Posted by Jesse Glick on January 31, 2010 at 02:59 AM PST #

I would have thought the same. Tried that too. But then there's a class cast problem or as Toni puts it in an e-mail to me: "
One small thing: has to be excluded due to a bug. Something get's the WindowManager from Lookup and tries to cast it to a concrete implementation. This leads to an exception. If that could easily be fixed we could probably also reuse the window system functionality like persistence and launching windows automatically."

Posted by Geertjan Wielenga on January 31, 2010 at 06:52 AM PST #

This is incredibly cool! I asked about this "feature" on NB forum, without any concrete answer. Now, you gave me the answer with an "example" as a bonus. IMHO, you really deserve a "NB-guru" status! :)

Posted by Eduardo Costa on January 31, 2010 at 07:10 PM PST #

Thanks Eduardo. Would be great to get a screenshot from you when you've made some progress with creating your own window system. :-)

Posted by Geertjan Wielenga on January 31, 2010 at 09:59 PM PST #

Nice! Worked like a charm! Using Feed Reader sample, I created a "window manager" module with your MyWindowManager and voila! Good bye NB WM and welcome lots of ideas! :)

PS: I will post some screenshots as soon as I have something useful

Posted by Eduardo Costa on February 03, 2010 at 11:02 PM PST #

Nice! Worked like a charm using Feed Reader sample! Good bye NB WM and welcome lots of ideas!

PS: I will post some screenshots as soon as I have something useful

Posted by Eduardo Costa on February 03, 2010 at 11:03 PM PST #

An opened door on the 3rd dimension ? :-)

Posted by Vincent Cantin on February 09, 2010 at 11:20 PM PST #

You need to update your url for to this:

Posted by guest on April 15, 2012 at 06:26 AM PDT #

Thanks, done!

Posted by Geertjan on April 15, 2012 at 07:35 AM PDT #

Thinking one step further:
Is it possible to start MyWindowManager in fullscreen mode?
So I could think of a desktop-manager for Java apps...

Posted by guest on June 17, 2013 at 11:13 PM PDT #

import org.openide.awt.Actions;

public class FullScreenAtStartUp implements Runnable {

public void run() {
Actions.forID("Window", "").actionPerformed(null);


Posted by Geertjan on June 17, 2013 at 11:48 PM PDT # can not find the function "invokeWhenUIReady" and "PROP_TC_OPENED" and "PROP_TC_CLOSED".

Posted by guest on June 18, 2013 at 01:56 PM PDT #

can not find the function "invokeWhenUIReady" and two fields "PROP_TC_OPENED" and "PROP_TC_CLOSED".

Posted by guest on June 18, 2013 at 02:03 PM PDT #

Two seconds of googling the terms "invokeWhenUIReady netbeans" gives me the answer to your question. Try google. It's free. It works.

Posted by Geertjan on June 18, 2013 at 02:47 PM PDT #

Is this windows manager still keep the tearing off tab feature of netbeans platform? Are the Main Window and View1 windows independent (if Main window is closed and View1 window is still open)?

Thank you very much!

Posted by guest on June 28, 2013 at 12:26 PM PDT #

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Geertjan Wielenga (@geertjanw) is a Principal Product Manager in the Oracle Developer Tools group living & working in Amsterdam. He is a Java technology enthusiast, evangelist, trainer, speaker, and writer. He blogs here daily.

The focus of this blog is mostly on NetBeans (a development tool primarily for Java programmers), with an occasional reference to NetBeans, and sometimes diverging to topics relating to NetBeans. And then there are days when NetBeans is mentioned, just for a change.


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