title: Disable a sortable?
body: <p>I have a draggable connected to a sortable:</p>
  
  <pre><code>$("#panelTarget").sortable({
      distance: '15'
  });
  
  var element = $('&lt;li&gt;Hello&lt;/li&gt;');
  element.appendTo('#panelSource');
  element.draggable();
  element.draggable("option", "connectToSortable", '#panelTarget');
  </code></pre>
  
  <p>at some point, I want to make it impossible for the user to drop items onto the sortable panel (panelTarget). I'm trying this:</p>
  
  <pre><code>$('#panelTarget').sortable( "disable" );
  </code></pre>
  
  <p>but I can still drop elements onto it, am I not interpreting the docs correctly?:</p>
  
  <pre><code>http://jqueryui.com/demos/sortable/#method-disable
  </code></pre>
  
  <p>how can I block the user from dropping stuff on the panel?</p>
  
  <p>Thanks</p>