import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

/**
 If you register an object of this class as a listener to any
 object of the class JFrame, the object will end the program
 and close the JFrame, if the user clicks the JFrame's 
 close-window button.
*/
public class WindowDestroyer extends WindowAdapter
{
    public void windowClosing(WindowEvent e)
    {
        System.exit(0);
    }
}