title: How to enable/disable and/or show/hide GWT MenuItem
body: <p>I am using GWT 2.5.1</p>
  
  <p>I have been struggling with this for hours now. How do you disable and/or hide a MenuItem in GWT.</p>
  
  <pre><code>menuItem.setEnabled(false); // DOES NOT WORK !!!
  menuItem.setVisible(false); // DOES NOT WORK !!!
  UIObject.setVisible(menuItem.getElement(), false); // DOES NOT WORK !!!
  menuItem.setScheduledCommand(null); // DOES NOT WORK !!!
  </code></pre>