uievent in Applet

import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
/**/
public class uievent extends Applet implements ActionListener
{
myframe frame;
Button open,close;
Button open1,close1;
public void init()
{
setLayout(new BorderLayout());
open=new Button("OPEN");
add(open,"North");
open.addActionListener(this);
close=new Button("CLOSE");
add(close,"South");
close.addActionListener(this);
close.setEnabled(false);
frame=new myframe("MY FIRST WINDOW");
frame.setSize(150,150);
open1=new Button("OPEN");
close1=new Button("CLOSE");
frame.add(close1,"North");
frame.add(open1,"South");
}
public void actionPerformed(ActionEvent e)
{
if(e.getSource()==open)
{
frame.show();
open.setEnabled(false);
close.setEnabled(true);
}
if(e.getSource()==close)
{
frame.setVisible(false);
open.setEnabled(true);
close.setEnabled(false);
}
}
}
class myframe extends Frame
{
myframe(String s)
{
super(s);
}
}