Jdesktop pane is not working as desired

Question

I took code from sun tutorial and added few lines of code, I using Jdesktop and internal frame here. my requirement is that i need to add one panel on Jdesktop pane. however when i tried to add panel, entire code behaved tht is not desired. internal frame not minimized/maximized. please let me know your thoughts and suggestions.
my changes with "My extra code" comment
import javax.swing.JInternalFrame;
public class MyInternalFrame extends JInternalFrame {
    static int openFrameCount = 0;
    static final int xOffset = 30, yOffset = 30;
    public MyInternalFrame() {
        super("Document #" + (++openFrameCount),
              true, //resizable
              true, //closable
              true, //maximizable
              true);//iconifiable
        setSize(300,300);
        //Set the window's location.
        setLocation(xOffset*openFrameCount, yOffset*openFrameCount);
import javax.swing.JDesktopPane;
import javax.swing.JLabel;
import javax.swing.JMenu;
import javax.swing.JMenuItem;
import javax.swing.JMenuBar;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import java.awt.event.*;
import java.awt.*;
public class InternalFrameDemo extends JFrame
                               implements ActionListener {
    JDesktopPane desktop;
    public InternalFrameDemo() {
        super("InternalFrameDemo");
        int inset = 50;
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        setBounds(inset, inset,
                  screenSize.width  - inset*2,
                  screenSize.height - inset*2);
        desktop = new JDesktopPane(); //a specialized layered pane
        // My extra code
        desktop.setLayout(new BorderLayout());
        JPanel panel = new JPanel(new BorderLayout());
        panel.add(new JLabel("Dummy Label"),BorderLayout.CENTER);
        desktop.add(panel, BorderLayout.CENTER);
        // my extra code ended here
        createFrame(); //create first "window"
        setContentPane(desktop);
        setJMenuBar(createMenuBar());
        desktop.setDragMode(JDesktopPane.OUTLINE_DRAG_MODE);
    protected JMenuBar createMenuBar() {
        JMenuBar menuBar = new JMenuBar();
        JMenu menu = new JMenu("Document");
        menu.setMnemonic(KeyEvent.VK_D);
        menuBar.add(menu);
        JMenuItem menuItem = new JMenuItem("New");
        menuItem.setMnemonic(KeyEvent.VK_N);
        menuItem.setAccelerator(KeyStroke.getKeyStroke(
                KeyEvent.VK_N, ActionEvent.ALT_MASK));
        menuItem.setActionCommand("new");
        menuItem.addActionListener(this);
        menu.add(menuItem);
        menuItem = new JMenuItem("Quit");
        menuItem.setMnemonic(KeyEvent.VK_Q);
        menuItem.setAccelerator(KeyStroke.getKeyStroke(
                KeyEvent.VK_Q, ActionEvent.ALT_MASK));
        menuItem.setActionCommand("quit");
        menuItem.addActionListener(this);
        menu.add(menuItem);
        return menuBar;
    public void actionPerformed(ActionEvent e) {
        if ("new".equals(e.getActionCommand())) { //new
            createFrame();
        } else { //quit
            quit();
    //Create a new internal frame.
    protected void createFrame() {
        MyInternalFrame frame = new MyInternalFrame();
        frame.setVisible(true); //necessary as of 1.3
        desktop.add(frame);
        try {
            frame.setSelected(true);
        } catch (java.beans.PropertyVetoException e) {}
    protected void quit() {
        System.exit(0);
    private static void createAndShowGUI() {
        JFrame.setDefaultLookAndFeelDecorated(true);
        InternalFrameDemo frame = new InternalFrameDemo();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    public static void main(String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
}Thanks,

Answer 1

Please read the relevant parts of the APi for JDesktopPane, DesktopManager and JLayeredPane to understand the code.import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import javax.swing.*;
public class PanelAtBottom {
  public static void main(String[] args) {
    SwingUtilities.invokeLater(new Runnable() {
      @Override
      public void run() {
        new PanelAtBottom().makeUI();
  public void makeUI() {
    final JDesktopPane desktopPane = new JDesktopPane();
    for (int i = 0; i < 5; i++) {
      JInternalFrame internalFrame = new JInternalFrame("Frame " + i);
      internalFrame.setIconifiable(true);
      internalFrame.setBounds(i * 10, i * 10, 200, 200);
      internalFrame.setVisible(true);
      desktopPane.add(internalFrame);
    final JPanel panel = new JPanel();
    panel.add(new JLabel("Label"));
    panel.add(new JButton("Button"));
    desktopPane.add(panel, JLayeredPane.DEFAULT_LAYER, -1);
    desktopPane.addComponentListener(new ComponentAdapter() {
      @Override
      public void componentResized(ComponentEvent e) {
        panel.setSize(desktopPane.getSize());
    desktopPane.setDesktopManager(new DefaultDesktopManager() {
      @Override
      public void iconifyFrame(JInternalFrame f) {
        super.iconifyFrame(f);
        desktopPane.moveToBack(panel);
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setContentPane(desktopPane);
    frame.setSize(600, 300);
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
}db