Excellent, didn't know about that! It looks really nice.
Although I had to give write access to the www-data user for this directory
/usr/local/lib/python2.7/dist-packages/TracWikiExtras-0.13.2dev-py2.7.egg/tracwikiextras/htdocs/css/
to create "boxes-300.css" and "boxes-300-toc.css".