title: Disabling and enabling jquery UI droppable not working
body: <p>I am trying to make a div that when it holds a droppable element, you won;t be able to drop another one on top of it, but when the draggable is removed - you can.
  I use </p>
  
  <pre><code>$("#trash").droppable({
      out: function() {
          $( this ).droppable( "option", "disabled", false );
      },
      drop: function( event, ui ) {
          $( this ).droppable( "option", "disabled", true );
      }
  });
  </code></pre>
  
  <p>But it <code>#trash</code> remains disabled after I move the droppable out, I don't understand why.
  <a href="http://jsfiddle.net/vMQVy/38/" rel="nofollow">http://jsfiddle.net/vMQVy/38/</a></p>