Terrapins Sky: [Swing][Resolved] JMenuBar items disappearing behind panel

The problem is JMenuBar item hide behind a Label element, and this is the code:

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.Label;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class USD2EUR extends JFrame implements ActionListener{
    private JMenuBar menuBar;
    private JMenu     mAction;
    private JMenuItem mConvert;
    private JMenuItem mExit;
    private Label eurResultLabel;
    private JTextField usdTextField;
    private double exchangeRate = 0.89;

    public USD2EUR(){
        JFrame frame = new JFrame("USD2EUR");
        frame.setLayout(new BorderLayout());
        setPreferredSize(new Dimension(200, 115));

        //MenuBar
        menuBar = new JMenuBar();
        setJMenuBar(menuBar);
        mAction = new JMenu("Action");
        menuBar.add(mAction);

        mConvert = new JMenuItem("Convert");
        mAction.add(mConvert);
        mConvert.addActionListener(this);

        mExit    = new JMenuItem("Exit");
        mAction.add(mExit);
        mExit.addActionListener(this);

        //Content
        JPanel panel   = new JPanel();
        panel.setLayout(new GridLayout(2, 1));
        usdTextField   = new JTextField("USD Amount");
        panel.add(usdTextField);
        eurResultLabel = new Label("Label");
        panel.add(eurResultLabel);
        add(panel);

        setVisible(true); //frame.setVisible(true);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        pack();
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        Object source = e.getSource();
        if(source == mConvert){
            double usdAmount = Double.parseDouble(usdTextField.getText());
            double eurAmount = usdAmount * exchangeRate;
            eurResultLabel.setText(Double.toString(eurAmount));
        }else if(source == mExit){
            System.exit(0);
        }
    }

    public static void main(String[] args) {
        new USD2EUR();
    }

}

According Andrew Thompson in stackoverflow.com : "Don't mix Swing with any AWT components unless you have very good reason to do so.", so i change the Label (java.awt.Label) to a JLabel (javax.swing.JLabel).

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.Label;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class USD2EUR extends JFrame implements ActionListener{
    private JMenuBar menuBar;
    private JMenu     mAction;
    private JMenuItem mConvert;
    private JMenuItem mExit;
    private JLabel eurResultLabel;
    private JTextField usdTextField;
    private double exchangeRate = 0.89;

    public USD2EUR(){
        JFrame frame = new JFrame("USD2EUR");
        frame.setLayout(new BorderLayout());
        setPreferredSize(new Dimension(200, 115));

        //MenuBar
        menuBar = new JMenuBar();
        setJMenuBar(menuBar);
        mAction = new JMenu("Action");
        menuBar.add(mAction);

        mConvert = new JMenuItem("Convert");
        mAction.add(mConvert);
        mConvert.addActionListener(this);

        mExit    = new JMenuItem("Exit");
        mAction.add(mExit);
        mExit.addActionListener(this);

        //Content
        JPanel panel   = new JPanel();
        panel.setLayout(new GridLayout(2, 1));
        usdTextField   = new JTextField("USD Amount");
        panel.add(usdTextField);
        eurResultLabel = new JLabel("Label");
        panel.add(eurResultLabel);
        add(panel);

        setVisible(true); //frame.setVisible(true);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        pack();
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        Object source = e.getSource();
        if(source == mConvert){
            double usdAmount = Double.parseDouble(usdTextField.getText());
            double eurAmount = usdAmount * exchangeRate;
            eurResultLabel.setText(Double.toString(eurAmount));
        }else if(source == mExit){
            System.exit(0);
        }
    }

    public static void main(String[] args) {
        new USD2EUR();
    }

}