Thread: Why will this gui window not close

package newestlatestgui;
 
import java.awt.*;
import java.awt.event.*;
 
 
 
    public class NewestLatestGui extends Frame implements WindowListener {
        public GUIFrame(String title) {
            super(title);
            setBackground(SystemColor.control);
 
            addWindowListener(this);
        }
 
        public void setVisible(boolean visible) {
            if (visible) {
                Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
                setLocation((d.width-getWidth())/2, (d.height-getHeight())/2);
 
            }
 
            super.setVisible(visible);
        }
    }
 
    public void windowClosing(WindowEvent p1) {
        dispose();
        System.exit(0);
    }
 
    public void windowDeactivated(WindowEvent p1) {}
    public void windowClosed(WindowEvent p1) {}
    public void windowDeiconfied(WindowEvent p1) {}
    public void WindowOpened(WindowEvent p1) {}
    public void windowIconified(WindowEvent p1) {}
    public void windowActivated(WindowEvent p1) {}
 
 
 
}

 
package newestlatestgui;
 
 
import java.awt.*;
import java.awt.event.*;
 
 
public class SimpleFrameTest {
 
    public static void main(String argsp[]) {
        Frame frame = new Frame("Simple Frame Test");
        frame.setSize(400,300);
        frame.setVisible(true);
    }
 
}

Why won't the window close?

Thank you John Joe