Sub-classing JComponent directly is probably more appropriate.  Even  
easier is using a ready-made library such as JFreechart.

You might get better advice from comp.lang.java.gui (this reply is  
cross-posted with follow-ups set to comp.lang.java.gui only).

Dan.

This is how I would do it.  You will need to make it look better but the
big pieces are all here.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;

public class test {
    public static void main(String[] args) {
        Runnable r = new Runnable() {
            public void run() {
                class ChartPanel extends JPanel {
                    private int value = 0;

                    public ChartPanel() {
                        setPreferredSize(new Dimension(200,150));
                    }

                    public void setValue(int v) {
                        value = v;
                    }

                    public void paintComponent(Graphics g) {
                        int w = getWidth();
                        int h = getHeight();
                        g.setColor(Color.WHITE);
                        g.fillRect(0,0,w,h);
                        g.setColor(Color.BLUE);
                        g.drawString("100%",0,10);
                        g.drawString("0%",0,h);
                        g.fillRect(w/3,h - (h * value / 100),
                         w/3,h * value / 100);
                    }
                }
                JFrame f = new JFrame();
                f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

                final ChartPanel cp = new ChartPanel();
                SpinnerNumberModel nm =
                 new SpinnerNumberModel(0,0,100,1);
                JSpinner sp = new JSpinner(nm);
                sp.addChangeListener(new ChangeListener() {
                    public void stateChanged(ChangeEvent ce) {
                        JSpinner sp = (JSpinner)ce.getSource();
                         cp.setValue(
                          ((Integer)sp.getValue()).intValue());
                    }
                });
                JTabbedPane tp = new JTabbedPane();
                tp.add(sp,"Changer");
                tp.add(cp,"Chart");

                f.add(tp);
                f.pack();
                f.setVisible(true);
            }
        };
        EventQueue.invokeLater(r);
    }
}

<snip>

Thanks for the quick replies. I think I have it working now... It seems my
approach was wrong. Here is how I got it to work the way I needed.
1. Turned off the computer
2. Had <sufficient # of beers> to feel better about life.
3. Had a nice steak dinner.
4. Turned computer back on
5. It worked!

I guess what happened was I was running the wrong version or something. I
kept making changes, and I guess I saved them in the wrong place. Anyway -
once I rebooted and tried again - it just worked.

I think I will apply my new 5 step approach more often...