title: jQuery sortable list placeholder issue
body: <p>I have a sortable list. I have managed to sort into multilevel. But when an element from first level depth is inserted into second level depth the placeholder keeps running violently. </p>
  
  <pre><code>$('.sortable').sortable({ 
      connectWith:    '.sortable',
      cursor:         'move',
      placeholder:    'sortable-placeholder',
      handle:         '.block-title',
      cursorAt:       { left: 150, top: 17 },
      /*tolerance:      'pointer',*/
      scroll:         false,
      zIndex:         9999,
  });
  $('.sortable').disableSelection();
  </code></pre>
  
  <p>Here is my <a href="http://jsfiddle.net/melvinstanly/c7PGP/61/" rel="nofollow noreferrer">fiddle</a></p>