Problems with JLayeredPane

Question

I have the attached program that is supposed to show a red background that has a transparent green rectangle on top. The rectangle is created via a mouse drag. Running the program just gives a gray window with nothing happening when I drag the mouse. What is wrong?
import java.awt.*;
import java.util.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
import static java.lang.Math.*;
public class TestLayers extends JFrame{
     public JLayeredPane layeredPane;
     public Background background;
     public JPanel board;
     public Overlay overlay;
     public Point mPress, mRelease;
     public int left = 0, top = 0, width = 0, height= 0;
          MouseListener ml = new MouseAdapter() {
               public void mousePressed(MouseEvent e) {
                         mPress = e.getPoint();
               public void mouseReleased(MouseEvent e) {
                         mRelease = e.getPoint();
                         width = abs(mPress.x - mRelease.x);
                         height = abs(mPress.y - mRelease.y);
                         if (mPress.y < mRelease.y) top = mPress.y;
                         else top = mRelease.y;
                         if (mPress.x < mRelease.x) left = mPress.x;
                         else left = mRelease.x;
                         overlay.repaint();
     public TestLayers() {
          Dimension sz = new Dimension(500,500);
          layeredPane = new JLayeredPane();
          layeredPane.setPreferredSize( sz );
          getContentPane().add(layeredPane, BorderLayout.CENTER);
          layeredPane.setOpaque(true);
          background = new Background();
          layeredPane.add(background, JLayeredPane.DEFAULT_LAYER);
          overlay = new Overlay();
          layeredPane.add(overlay, JLayeredPane.PALETTE_LAYER);
          layeredPane.addMouseListener(ml);
          layeredPane.setVisible(true);
public static void main (String args[]) {
JFrame frame = new TestLayers();
          frame.setDefaultCloseOperation( DISPOSE_ON_CLOSE );
frame.pack();
frame.setResizable( false );
frame.setLocationRelativeTo( null );
frame.setVisible(true);
     public class Background extends JPanel {
          public Background() {
          public void paintComponent(Graphics g) {
               super.paintComponent(g);
               g.setColor(Color.red);
               g.fillRect(0,0,500,500);
     public class Overlay extends JPanel {
          public Overlay() {
          public void paintComponent(Graphics g) {
               Color myColor = new Color(0, 255, 0, 120);
               g.fillRect(left, top, width, height);
}

Answer 1

I made the changes you suggested, still a gay frame.
import java.awt.*;
import java.util.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
import static java.lang.Math.*;
public class TestLayers extends JFrame{
     public  JLayeredPane layeredPane;
     public Background background;
     public JPanel board;
     public Overlay overlay;
     public Point mPress, mRelease;
     public int left = 0, top = 0, width = 0, height= 0;
          MouseListener ml = new MouseAdapter() {
               public void mousePressed(MouseEvent e) {
                         mPress = e.getPoint();
               public void mouseReleased(MouseEvent e) {
                         mRelease = e.getPoint();
                         width = abs(mPress.x - mRelease.x);
                         height = abs(mPress.y - mRelease.y);
                         if (mPress.y < mRelease.y) top = mPress.y;
                         else top = mRelease.y;
                         if (mPress.x < mRelease.x) left = mPress.x;
                         else left = mRelease.x;
                         overlay.repaint();
     public TestLayers() {
          Dimension sz = new Dimension(500,500);
          layeredPane = new JLayeredPane();
          layeredPane.setPreferredSize( sz );
          getContentPane().add(layeredPane, BorderLayout.CENTER);
          layeredPane.setOpaque(true);
          background = new Background();
          background.setPreferredSize( sz );
          layeredPane.add(background, JLayeredPane.DEFAULT_LAYER);
          overlay = new Overlay();
          layeredPane.add(overlay, JLayeredPane.PALETTE_LAYER);
          layeredPane.addMouseListener(ml);
          layeredPane.setVisible(true);
    public static void main (String args[]) {
        JFrame frame = new TestLayers();
          frame.setDefaultCloseOperation( DISPOSE_ON_CLOSE );
        frame.pack();
        frame.setResizable( false );
        frame.setLocationRelativeTo( null );
        frame.setVisible(true);
     public class Background extends JPanel {
          public Background() {
          public void paintComponent(Graphics g) {
               super.paintComponent(g);
               g.setColor(Color.red);
               g.fillRect(0,0,500,500);
     public class Overlay extends JPanel {
          public Overlay() {
          public void paintComponent(Graphics g) {
               Color myColor = new Color(0, 255, 0, 120);
               g.setColor(myColor);
               g.fillRect(left, top, width, height);
}