title: Adding a delay to droppable event
body: <p>I have a droppable element with a dropover event handler. Dragging an element over the droppable expands a node. However, I want to add a delay so the node does not expand immediately, i.e. you have to hold the draggable over the droppable for a second before it expands.</p>
  
  <pre><code>droppable.over = function(event, ui) {
      // expand node if dragover lasts 1000 milliseconds
      node.expand();
  }; 
  </code></pre>
  
  <p>My first thought was to simply use <code>setTimeout</code> on <code>node.expand()</code>, but this doesn't do what I want, it simply delays the node expanding. It doesn't look like there's any configuration I can set to achieve this, so I'm wondering how I can do it.</p>