title: jQuery toggleClass working but not animating
body: <p>This code <code>$(this).data('parentWidget').toggleClass(COLLAPSE_CLASS, 1000);</code> bound to a button click, is successfully toggling the COLLAPSE_CLASS on and off. However, the effect is not animating.</p>
  
  <p>In the css, the original element has a defined height:85px. When the collapse class is added .collapse { height:20px; } only the height changes.</p>
  
  <p>As I mentioned, this works like a charm in terms of toggling the height. What I don't see is any kind of transition effect. What are the conditions under which such a simple transition effect might not work? Needless to say the <a href="http://jqueryui.com/demos/toggleClass/" rel="nofollow">jQuery documentation</a> on the subject is sparse.</p>