title: key up event not firing on letter/number keys
body: <p>When i release a letter or number key i don't get key up events. When i release enter/alt/arrows/space i see the output. key down fires for all keys. Any ideas on what is it?</p>
  
  <p>Edit: for clarity - Keys is the main class.</p>
  
  <p>Edit 2: I am using flexSDK 4.6</p>
  
  <pre><code>package {
  
  import flash.display.Sprite;
  import flash.events.KeyboardEvent;
  
  public class Keys extends Sprite {
      public function Keys() {
          stage.addEventListener(KeyboardEvent.KEY_DOWN, onKeyDown);
          stage.addEventListener(KeyboardEvent.KEY_UP, onkeyUp);
      }
      private function onKeyDown(e:KeyboardEvent){
          trace("1 "+e.keyCode);
      }
      private function onkeyUp(e:KeyboardEvent){
          trace("0 "+e.keyCode);
      }
  }
  }
  </code></pre>
  
  <p>Things get interesting if i add a text field with type of "input" to stage. If i focus the text field keyUp events start working if i however press keys when stage has focus keyUp events do not fire.</p>