Stop creating a new dialog

I'm trying to create a Java Swing dialog, but I don't want the dialog to focus on what is currently focused. For example, if you are editing the word doc and another application creates a dialog, you should see the dialog, but the word doc must remain in focus so that you can continue editing.

I have tested the following code on Mac OSX and Ubuntu 12.04. On Mac, the code creates dialog boxes that don't take focus as I want. On Ubuntu, dialogs take focus and I cannot enter them while they are being created.

I really hope this is not the case for the operating system. Is there a way to achieve what I am trying to do on all platforms (or at least Ubuntu)?

import javax.swing.*;
import java.awt.Color;
import java.util.Random;

public class Focus {
    private static Random r = new Random();

    public static void main(String[] args) {
        while(true) {   
            try {
                Thread.sleep(500);
                createObject(r.nextInt(1000), r.nextInt(600));
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    public static void createObject(int x, int y) {
        JDialog testDialog = new JDialog();
        testDialog.setSize(50, 50);
        testDialog.setLocation(x, y);
        testDialog.setAlwaysOnTop(true);
        testDialog.setUndecorated(true);
        testDialog.setFocusable(false);
        testDialog.setEnabled(false);
        testDialog.setVisible(true);
    }
}