import java.awt.*; 
import java.applet.Applet;

public class CanvasApplet extends Applet {
  SubCanvas0 c0;
  SubCanvas1 c1;

  public void init() {
    setBackground(Color.cyan);
    
    c0 = new SubCanvas0();
    c0.resize(200,150);
    c0.setBackground(Color.black);
    add(c0);
    
    c1 = new SubCanvas1();
    c1.resize(200,150);
    c1.setBackground(Color.white);
    add(c1);

  }
}
  
class SubCanvas0 extends Canvas {
  int mx, my;  // マウス位置
  
  public void paint(Graphics g) {
    g.setColor(Color.white);
    g.fillOval(mx-10, my-10, 20, 20);
  }
  
  public boolean mouseDown(Event evt, int x, int y) {
  	mx = x;
  	my = y;
  	repaint();
  	return true;
  } 
} 

class SubCanvas1 extends Canvas {
  int mx, my;  // マウス位置
  
  public void paint(Graphics g) {
    g.setColor(Color.black);
    g.fillOval(mx-10, my-10, 20, 20);
  }
  
  public boolean mouseDown(Event evt, int x, int y) {
  	mx = x;
  	my = y;
  	repaint();
  	return true;
  } 
}