On the windows system, the constructor for JWindow that accepts an owner window and a graphics configuration throws an IllegalArgumentException. The constructor works fine on solaris and linux. This can be seen from the following code :

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

public class JWindowTest{
public static void main(String[] args){
JWindowTest jwn = new JWindowTest();
}

public JWindowTest(){
GraphicsConfiguration gc;
JFrame f = new JFrame("TEST");
JWindow parent = new JWindow(f);
JWindow child;

f.setSize(10,10);
f.setVisible(true);

GraphicsEnvironment ge = GraphicsEnvironment.
getLocalGraphicsEnvironment();
GraphicsDevice[] gs = ge.getScreenDevices();
GraphicsDevice gd = gs[0];
GraphicsConfiguration[] gcon = gd.getConfigurations();
gc = gcon[0];
System.out.println(gc);

child = new JWindow(parent , gc);
System.out.println("Done");
}
}

C:\work\temp>java -showversion JWindowTest
java version "1.4.0-beta_refresh"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-beta_refresh-b71)
Java HotSpot(TM) Client VM (build 1.4-internal, mixed mode)

Exception in thread "main" java.lang.IllegalArgumentException: null owner window

        at java.awt.Window.ownedInit(Window.java:349)
        at java.awt.Window.<init>(Window.java:344)
        at javax.swing.JWindow.<init>(JWindow.java:197)
        at JWindowTest.<init>(JWindowTest.java:27)
        at JWindowTest.main(JWindowTest.java:6)


Please see the comments section where I have inadvertantly put the suggested fix