Run the following test case and notice that when the app is brought up
the panel is painted twice.

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

public class Test {
    public static void main(String[] args) throws Throwable {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                show();
            }
        });
    }

    private static void show() {
        JFrame frame = new JFrame("TEST");
        JComponent button = new JPanel() {
            public void paint(Graphics g) {
                super.paint(g);
                System.out.println("----------PAINTING---------------------");
                System.out.println("widget bounds: " + getBounds());
                System.out.println("clip: " + g.getClip());
            }
        };
        frame.setLayout(new FlowLayout());
        frame.add(button);
        frame.pack();
        frame.show();
    }
}