title: WPF Grid/WrapPanel AutoSize Animation
body: <p>I have the following layout in WPF</p>
  
  <pre><code>&lt;grid&gt;
  &lt;row height=auto&gt;
  &lt;border&gt;
  &lt;listbox&gt;
  &lt;border?
  &lt;/row&gt;
  &lt;row height=*&gt;
  &lt;othercontent&gt;
  &lt;/row&gt;
  &lt;/grid&gt;
  </code></pre>
  
  <p>Using MVVM and have listbox itemsource bound.  I am using a wrapPanel in the grid, and have scrolling disabled so the Grid row height will grow and shrink based on the list box contents.  This is all working fine.</p>
  
  <p>What I would like, is to be able to animate the growing and shrinking of the listbox (or the border containing it, or the grid row that has the auto-height).  What element should I be using - a trigger on SizeChanged on the border?</p>
  
  <p>Also I when my ItemsSource changes, I would like my listbox items to fade out, then the resize, then the new items to fade in.</p>
  
  <p>Any help much appreciated.
  Thanks,
  Chris</p>