title: I would like this jquery ui code explained please
body: <p>I was reading this code (<a href="http://jqueryui.com/droppable/#photo-manager" rel="nofollow">http://jqueryui.com/droppable/#photo-manager</a>), 
  but couldn't understand one specific line </p>
  
  <pre><code>var $gallery = $( "#gallery" ),
      $trash = $( "#trash" ); 
  
  $( "li", $gallery ).draggable({ //This is the line a I can't understand well
          cancel: "a.ui-icon", 
          revert: "invalid", 
          containment: "document",
          helper: "clone",
          cursor: "move"
  });
  </code></pre>
  
  <p>why is the $gallery there? it's not making the $gallery draggable, only <code>&lt;li&gt;</code> is draggable.</p>
  
  <p>It seems that only <code>&lt;li&gt;</code> inside <code>#gallery</code> can be dragged, but that's easily done with <code>$("#gallery li")</code> or <code>$("#gallery &gt; li")</code></p>
  
  <p>So what's different?  </p>