DrawMode

import java.applet.*;
import java.awt.*;
import java.awt.event.*;

public class DrawMode extends Applet
{
public void init()
{
Button butt = new Button("repaint");
add(butt);
butt.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent evt) {
repaint();
}

});

}

public void update(Graphics g){
paint(g);
}

public void paint(Graphics g){
g.setPaintMode();
g.fillOval(0, 0, 30, 30);

g.setXORMode(getBackground());
g.fillOval(40, 0, 30, 30);
}

}