mała przerobka [dodanie buttona czyszczącego rysunek]

siemanko, prosze o drobna korekte programu w javie...tzn dodanie buttona czyszczacego rysunek:

zamieszczam kodzik:
import java.awt.;
import java.awt.event.;

public class Brush1 extends Applet
implements MouseMotionListener {

int width, height;
Image backbuffer;
Graphics backg;

public void init() {
width = getSize().width;
height = getSize().height;

  backbuffer = createImage( width, height );
  backg = backbuffer.getGraphics();
  backg.setColor( Color.black );
  backg.fillRect( 0, 0, width, height );
  backg.setColor( Color.green );

  addMouseMotionListener( this );

}

public void mouseMoved( MouseEvent e ) { }
public void mouseDragged( MouseEvent e ) {
int x = e.getX();
int y = e.getY();
backg.fillOval(x-5,y-5,10,10);
repaint();
e.consume();
}

public void update( Graphics g ) {
g.drawImage( backbuffer, 0, 0, this );
}

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