title: X toolkit, How to access rendered canvas data in Chromium
body: <p>With the <a href="http://lessons.goxtk.com/00/" rel="nofollow">http://lessons.goxtk.com/00/</a> and I am trying to get the data as an image ( toDataURL('image/webp') ) from the canvas in Chromium  31.0.1650.63 (debian). After loading the page, I typed at the javascript console the followings :</p>
  
  <pre><code>canvas = document.getElementsByTagName("canvas")[0]; // get canvas
  canvas.toDataURL('image/webp'); // get data in a Chromium-compatible format 
  </code></pre>
  
  <p>But, what I got as data is a black picture at the size of the canvas, without the xtk rendered content. Is there a way to access the xtk's canvas data ?</p>
  
  <p>Thanks in advance</p>