Java JFrame manager

import java.awt.Dimension;
import java.awt.Point;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JOptionPane;

public class Main extends WindowAdapter {
   public int numWindows = 0;
   private Point lastLocation = null;
   private int maxX = 500;
   private int maxY = 500;

   public Main() {
      Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
      maxX = screenSize.width - 50;//from   w w w . j ava  2  s . co m
      maxY = screenSize.height - 50;
      makeNewWindow();
   }

   public void makeNewWindow() {
      JFrame frame = new MyFrame(this);
      numWindows++;
      System.out.println("Number of windows: " + numWindows);

      if (lastLocation != null) {
         // Move the window over and down 40 pixels.
         lastLocation.translate(40, 40);
         if ((lastLocation.x > maxX) || (lastLocation.y > maxY)) {
            lastLocation.setLocation(0, 0);
         }
         frame.setLocation(lastLocation);
      } else {
         lastLocation = frame.getLocation();
      }

      System.out.println("Frame location: " + lastLocation);
      frame.setVisible(true);
   }

   // This method must be evoked from the event-dispatching thread.
   public void quit(JFrame frame) {
      if (quitConfirmed(frame)) {
         System.out.println("Quitting.");
         System.exit(0);
      }
      System.out.println("Quit operation not confirmed; staying alive.");
   }

   private boolean quitConfirmed(JFrame frame) {
      String s1 = "Quit";
      String s2 = "Cancel";
      Object[] options = { s1, s2 };
      int n = JOptionPane.showOptionDialog(frame, "Windows are still open.\nDo you really want to quit?",
            "Quit Confirmation", JOptionPane.YES_NO_OPTION, JOptionPane.QUESTION_MESSAGE, null, options, s1);
      if (n == JOptionPane.YES_OPTION) {
         return true;
      } else {
         return false;
      }
   }

   public void windowClosed(WindowEvent e) {
      numWindows--;
      System.out.println("Number of windows = " + numWindows);
      if (numWindows <= 0) {
         System.out.println("All windows gone.  Bye bye!");
         System.exit(0);
      }
   }

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

class MyFrame extends JFrame {
   protected Dimension defaultSize = new Dimension(200, 200);
   protected Main framework = null;

   public MyFrame(Main controller) {
      super("New Frame");
      framework = controller;
      setDefaultCloseOperation(DISPOSE_ON_CLOSE);
      addWindowListener(framework);

      JMenu menu = new JMenu("Window");
      menu.setMnemonic(KeyEvent.VK_W);
      JMenuItem item = null;
      // close
      item = new JMenuItem("Close");
      item.setMnemonic(KeyEvent.VK_C);
      item.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent e) {
            System.out.println("Close window");
            MyFrame.this.setVisible(false);
            MyFrame.this.dispose();
         }
      });
      menu.add(item);

       JMenuBar menuBar = new JMenuBar();
      menuBar.add(menu);
      setJMenuBar(menuBar);

      setSize(defaultSize);
   }
}