title: handle key combination when an action is already registered for it
body: <p>My use case would be to handle the <kbd>Ctrl (Cmd) + A</kbd> key combination in a <code>TextCellEditor</code>s <code>Text</code> control which opens on an "editable" label using gef (language is scala, sorry about that):</p>
  
  <pre><code>text.addKeyListener(new KeyAdapter {
    override def keyPressed(e: KeyEvent) = {
      val ctrlKey = if (Util.isMac) SWT.COMMAND else SWT.CTRL
      if (e.stateMask == ctrlKey &amp;&amp; e.keyCode == 'a') {
        text.selectAll()
        e.doit = false
      }
    }
  })
  </code></pre>
  
  <p>But since a "global" action is registered for the whole gef <code>GraphicalEditor</code>, I don't even receive the event. </p>
  
  <p>How could I get around this and make the handler receive the key event?</p>