Full Screen Mode Isn't Full Screen

Possible Duplicate:
Java Fullscreen mode not working on Ubuntu

I am try to do 100% full screen mode, I am using Ubuntu 12.10, and on the left is the side bar and the top is the menu. When I run full screen mode it doesn't cover up those two menu bars, it sits next to them:

It should cover the left menu bar and the top black bar. Why doesn't it?

package sscce;

import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import javax.swing.JFrame;

public class Main extends JFrame{

    public Main(){
        GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
        GraphicsDevice myDevice = ge.getDefaultScreenDevice();
        this.setUndecorated(true);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        myDevice.setFullScreenWindow(this);
    }

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