title: KeyListener or TraverseListener in SWT Menu
body: <p>I'd like to be able to detect keyboard input (namely the TAB key) when an SWT menu is open, but it doesn't seem to broadcast any events when listeners are added with the <code>addListener</code> method, and there are no <code>addKeyListener</code> or <code>addTraverseListener</code> methods. </p>
  
  <p>I've also tried adding listeners to the control to which the menu is added (it's a popup menu) as well as the shell, but key events don't make it to those objects either.  </p>
  
  <p>It looks like the menu is an OS level control that eats up keyboard events.  Has anyone found a way to grab keystrokes from a popup menu?  Or is the only option to make my own non-OS popup menu?</p>