title: HTML5 Canvas hosted on Dropbox doesn't work with IE9
body: <p>Try this link on Firefox or Chrome:</p>
  
  <p><a href="http://dl.dropbox.com/u/34375299/aaa/index.html" rel="nofollow">http://dl.dropbox.com/u/34375299/aaa/index.html</a></p>
  
  <p>Notice a simple animation appears on a HTML5 canvas there.</p>
  
  <p>Load the same link in IE9, and it displays the fallback content inside the canvas tag: "Your browser does not appear to support HTML5..." - but IE9 has perfectly good canvas support!</p>
  
  <p>I'm using <code>&lt;!DOCTYPE html&gt;</code>, and if all the necessary files are downloaded and run in IE9 from disk, it works OK.  Also, the same page hosted on other providers (e.g. normal web servers rather than dropbox), it also works OK.</p>
  
  <p>What's different about dropbox that means IE9 won't show a canvas, and can I fix it?</p>