title: Set JMenu Margin not working
body: <p>I'm creating a JMenuBar with some JMenu and set margin in each JMenu. But the given margin not working in each JMenu. How to setMargin of JMenu correctly?</p>
  
  <pre><code> import javax.swing.*;
  
   public class JMenuDemo extends JFrame {
  
       private JMenuBar bar;
  
       public JMenuDemo() {
           super("Menu example");
           setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
           setVisible(true);
  
           initialize();
       }
  
       private void initialize() {
           bar = new JMenuBar();
           int menuHeight = 40;
  
           JMenu file = new JMenu("File");
           file.setPreferredSize(new java.awt.Dimension(50, menuHeight));
           file.setVerticalAlignment(javax.swing.SwingConstants.BOTTOM);
           file.setMargin(new java.awt.Insets(0, 0, 20, 0));
  
           JMenuItem newItem = new JMenuItem("New");
           file.add(newItem);
           JMenuItem openItem = new JMenuItem("Open");
           file.add(openItem);
           bar.add(file);
  
           JMenu test = new JMenu("Test");
           test.setPreferredSize(new java.awt.Dimension(60, menuHeight));
           test.setVerticalAlignment(javax.swing.SwingConstants.BOTTOM);
           test.setMargin(new java.awt.Insets(0, 0, 20, 0));
           bar.add(test);
  
           setJMenuBar(bar);
  
           getContentPane();
           setSize(400, 200);
       }
  
       public static void main(String[] args) {
           UIManager.getCrossPlatformLookAndFeelClassName(); 
  
           java.awt.EventQueue.invokeLater(new Runnable() {
               @Override
               public void run() {
                   new JMenuDemo();
               }
           });
       }
   }
  </code></pre>