Thread: Cannot add MenuBar to Frame on Mac OS

I am trying to add a menubar to a frame, when i execute the following program on Windows platform then i get the correct output where as the menubar does not appear in the frame if i execute it on Mac OS!!

 
import java.awt.*;
import java.awt.event.*;
public class menuDemo extends Frame implements WindowListener{
MenuBar mb;
Menu m1,m2,m3;
MenuItem mi1,mi2,mi3,mi4;
menuDemo(){
setLayout(new FlowLayout());
setSize(500,500);
mb=new MenuBar();
m1=new Menu("File");
m2=new Menu("New");
m3=new Menu("Save");
mi1=new MenuItem("one");
mi2=new MenuItem("two");
mi3=new MenuItem("three");
mi4=new MenuItem("Four");
Button b=new Button("hell");
add(b);
m1.add(mi1);
m1.add(mi2);
m2.add(mi3);
m3.add(mi4);
mb.add(m1);
mb.add(m2);
mb.add(m3);
setMenuBar(mb);
addWindowListener(this);
setVisible(true);
}
public static void main(String ar[]){
new menuDemo();
}
public void windowClosed(WindowEvent we){}
public void windowClosing(WindowEvent we){
dispose();
}
public void windowOpened(WindowEvent we){}
public void windowActivated(WindowEvent we){}
public void windowDeactivated(WindowEvent we){}
public void windowIconified(WindowEvent we){}
public void windowDeiconified(WindowEvent we){}
}