Progress Monitor not painting

Question

I'm working on a program that draws fractals, and I'm using a ProgressMonitor to display the length of the task. The ProgressMonitor is created and updated inside the method that calculates the fractal.
When I call it the first time in my main method, it shows up, displays properly and disappears. I can do this as many times as I want.
When I try to call it from the ActionListener associated with my 'recalculate' button the window for the ProgressMonitor appears, but the inside is never painted. After the task is complete it disappears again. Any idea what the problem could be?

Answer 1

* WaitCursor_Test.java
import java.awt.*;
import javax.swing.*;
public class WaitCursor_Test extends JFrame {
    public WaitCursor_Test() {
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setSize(400,300);
        setLocationRelativeTo(null);
        jPanel.add(jProgressBar);
        getContentPane().add(jPanel);
        setTitle("Wait 10 seconds");
        worker = new SwingWorker() {
            public Object construct() {
                setCursor(new Cursor(Cursor.WAIT_CURSOR));
                for( int i=0; i<=100; i++ ){
                    try{Thread.sleep(100);}catch(InterruptedException ex){}
                    jProgressBar.setValue(i);
                setCursor(new Cursor(Cursor.DEFAULT_CURSOR));
                jProgressBar.setVisible(false);
                setTitle("Done");
                return null;
        worker.start();
    public static void main(final String args[]) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                new WaitCursor_Test().setVisible(true);
     You need to download and compile the "SwingWorker" source code to be able to use it.
     Here it is:
     http://java.sun.com/products/jfc/tsc/articles/threads/src/SwingWorker.java
    private SwingWorker worker ;
    private JProgressBar jProgressBar = new JProgressBar();
    private JPanel jPanel = new JPanel();
}