title: dragover event is no not firing in firefox
body: <p>I'm working to simulate files and directories structure ,using drag and drop,
  my code is working fine in IE, Chrome but not working in Firefox ,
  while i'm searching i found this fiddle .</p>
  
  <pre><code>&gt;  http://jsfiddle.net/G9mJw/20/
  </code></pre>
  
  <p>same problem works on IE,Chrome but not Firefox ! </p>