title: Detect iframe content height change
body: <p>There are <strong>plenty</strong> of examples showing how to dynamically set an <code>iframe</code>'s height to its content.  This works perfect for me.  The problem I'm now having is that the content can change size without triggering <code>onload</code> (think hidden/expandable <code>div</code>s).</p>
  
  <p>Is there any way to detect when the size of the <code>iframe</code> content has changed?  This is on the same domain and no jQuery, please.</p>