%jigsaw not showing block in workspace

[bricecc]

When executing the example Jigsaw in IPython.ipynb, the blocks don't show and a warning is issued:

This happens when executing on my own server.

I have also tried extracting the html code which is generated and opening it in the browser. I get the same result:
blockly.html.zip

[EmericT]

Could it be related to #170 ?
The installation of the chromium extension Ignore X-frame header seems to solve the issue for me. However, I couldn't have it working in firefox, but I didn't try for too long.