title: Listen for change of class in jquery
body: <p>Is there a way in jquery to listen for a change to a node's class and then take some action on it if the class changes to a specific class? Specifically, I'm using the jquery tools tabs plugin with the slideshow and as the slideshow is playing, I need to be able to detect when the focus is on a particular tab/anchor so that I can unhide a specific div.</p>
  
  <p>In my specific example, I need to know when:</p>
  
  <pre><code>&lt;li&gt;&lt;a class="nav-video" id="nav-video-video7" href="#video7-video"&gt;Video Link 7&lt;/a&gt;&lt;/li&gt;
  </code></pre>
  
  <p>changes to the following with the class "current" added:</p>
  
  <pre><code>&lt;li&gt;&lt;a class="nav-video" id="nav-video-video7 current" href="#video7-video"&gt;Video Link 7&lt;/a&gt;&lt;/li&gt;
  </code></pre>
  
  <p>Then I want to unhide a div at that moment.</p>
  
  <p>Thanks!</p>