Visible no JBar quando o mouse estiver em cima da barra de menu

import java.awt.*;
 import java.awt.event.*;
 import javax.swing.*;
 
 public class Test extends JFrame {
 	/**
 	 * 
 	 */
 	private static final long serialVersionUID = -3110437340009570350L;
 
 	JMenu jm = new JMenu("A Menu");
 
 	JButton jb = new JButton("Desabilita Menu");
 
 	public Test() {
 		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 		Container content = (JPanel) getContentPane();
 		JMenuBar jmb = new JMenuBar();
 		jmb.add(jm);
 		setJMenuBar(jmb);
 		jm.add(new JMenuItem("Menu Item 1"));
 		jm.add(new JMenuItem("Menu Item 2"));
 		content.add(jb, BorderLayout.SOUTH);
 		jb.addActionListener(new ActionListener() {
 			public void actionPerformed(ActionEvent ae) {
 				jm.setEnabled(!jm.isEnabled());
 				jb.setText((jm.isEnabled() ? "Des" : "H") + "abilita  Menu");
 			}
 		});
 		this.setSize(200, 200);
 		this.setVisible(true);
 	}
 
 	public static void main(String[] args) {
 		new Test();
 	}
 }

bar.addMouseListener(new MouseAdapter(){

public void ??Movimentação do mouse???(MouseEvent event){

quando a seta do mouse estiver em cima do JMenuBar entao bar.setVisible(true);

}

});