paintbrush applet from jdk

this applet was taken from java development kit to give a java developer an innovative idea....
an applet for paint brush:

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

import java.util.Vector;

public class DrawTest extends Applet {
    public void init() {
setLayout(new BorderLayout());
DrawPanel dp = new DrawPanel();
add("Center", dp);
add("South",new DrawControls(dp));
    }

    public boolean handleEvent(Event e) {
switch (e.id) {
 case Event.WINDOW_DESTROY:
   System.exit(0);
   return true;
 default:
   return false;
}
    }

    public static void main(String args[]) {
Frame f = new Frame("DrawTest");
DrawTest drawTest = new DrawTest();
drawTest.init();
drawTest.start();

f.add("Center", drawTest);
f.resize(300, 300);
f.show();
    }
}

class DrawPanel extends Panel {
    public static final int LINES = 0;
    public static final int POINTS = 1;
    int   mode = LINES;
    Vector lines = new Vector();
    Vector colors = new Vector();
    int x1,y1;
    int x2,y2;
    int xl, yl;

    public DrawPanel() {
setBackground(Color.white);
    }

    public void setDrawMode(int mode) {
switch (mode) {
 case LINES:
 case POINTS:
   this.mode = mode;
   break;
 default:
   throw new IllegalArgumentException();
}
    }

    public boolean handleEvent(Event e) {
switch (e.id) {
 case Event.MOUSE_DOWN:
   switch (mode) {
     case LINES:
x1 = e.x;
y1 = e.y;
x2 = -1;
break;
     case POINTS:
     default:
colors.addElement(getForeground());
lines.addElement(new Rectangle(e.x, e.y, -1, -1));
x1 = e.x;
y1 = e.y;
repaint();
break;
   }
   return true;
 case Event.MOUSE_UP:
   switch (mode) {
     case LINES:
colors.addElement(getForeground());
lines.addElement(new Rectangle(x1, y1, e.x, e.y));
x2 = xl = -1;
break;
     case POINTS:
     default:
break;
   }
   repaint();
   return true;
 case Event.MOUSE_DRAG:
   switch (mode) {
     case LINES:
xl = x2;
yl = y2;
x2 = e.x;
y2 = e.y;
break;
     case POINTS:
     default:
colors.addElement(getForeground());
lines.addElement(new Rectangle(x1, y1, e.x, e.y));
x1 = e.x;
y1 = e.y;
break;
   }
   repaint();
   return true;
 case Event.WINDOW_DESTROY:
   System.exit(0);
   return true;
 default:
   return false;
}
    }

    public void paint(Graphics g) {
int np = lines.size();

/* draw the current lines */
g.setColor(getForeground());
g.setPaintMode();
for (int i=0; i < np; i++) {
   Rectangle p = (Rectangle)lines.elementAt(i);
   g.setColor((Color)colors.elementAt(i));
   if (p.width != -1) {
g.drawLine(p.x, p.y, p.width, p.height);
   } else {
g.drawLine(p.x, p.y, p.x, p.y);
   }
}
if (mode == LINES) {
   g.setXORMode(getBackground());
   if (xl != -1) {
/* erase the last line. */
g.drawLine(x1, y1, xl, yl);
   }
   g.setColor(getForeground());
   g.setPaintMode();
   if (x2 != -1) {
g.drawLine(x1, y1, x2, y2);
   }
}
    }
}


class DrawControls extends Panel {
    DrawPanel target;

    public DrawControls(DrawPanel target) {
this.target = target;
setLayout(new FlowLayout());
setBackground(Color.lightGray);
target.setForeground(Color.red);
CheckboxGroup group = new CheckboxGroup();
Checkbox b;
add(b = new Checkbox(null, group, false));
b.setBackground(Color.red);
add(b = new Checkbox(null, group, false));
b.setBackground(Color.green);
add(b = new Checkbox(null, group, false));
b.setBackground(Color.blue);
add(b = new Checkbox(null, group, false));
b.setBackground(Color.pink);
add(b = new Checkbox(null, group, false));
b.setBackground(Color.orange);
add(b = new Checkbox(null, group, true));
b.setBackground(Color.black);
target.setForeground(b.getForeground());
Choice shapes = new Choice();
shapes.addItem("Lines");
shapes.addItem("Points");
shapes.setBackground(Color.lightGray);
add(shapes);
    }

    public void paint(Graphics g) {
Rectangle r = bounds();

g.setColor(Color.lightGray);
g.draw3DRect(0, 0, r.width, r.height, false);
    }

    public boolean action(Event e, Object arg) {
if (e.target instanceof Checkbox) {
   target.setForeground(((Component)e.target).getBackground());
} else if (e.target instanceof Choice) {
   String choice = (String)arg;

   if (choice.equals("Lines")) {
target.setDrawMode(DrawPanel.LINES);
   } else if (choice.equals("Points")) {
target.setDrawMode(DrawPanel.POINTS);
   }
}
return true;
    }
}
output: