title: Disable single key input in flex
body: <p>I have an AdvancedDatagrid built up dynamically basing on xml data retrieved from http services.
  The last row contains columns totals and to simulate its footer behavior it has been foreseen a custom sortFunction, but it doesn't works for multiple columns sorting.
  Since I don't need multiple columns sorting, I preferred to:</p>
  
  <ul>
  <li>set adg.sortExpertMode = true;</li>
  <li>extend sortItemRenderer in order to hide the number indicating the sort order and so to avoid user to think multiple sort is possible</li>
  </ul>
  
  <p>Now, my problem is that if a user presses CTRL key and click on 1+n column, the standard adg class foresees the multiple sorting. So I thought I would be possibile to catch the pression of CTRL and to eliminate its effect.</p>
  
  <p>Below the code</p>
  
  <pre><code>private function keyHandler(event:KeyboardEvent):void{
  if (event.ctrlKey == true){
     event.stopImmediatePropagation();
  }
  }
  </code></pre>
  
  <p>It doesn't work, is there a way to make it possible??
  THanks in advance!</p>
  
  <p>Enrico</p>