> maybe we can ask if @AlexandreAbraham is willing a version on pypi that is easy_installable? or we can add it to an mne.external module if it's not too long in terms of lines.

Pynax is far from being mature... The main element missing being the documentation. As you can see in the commits, I completely redesigned it two months ago to make it more intuitive and efficient (which I consider successful because some people with poor knowledge in matplotlib managed to use it in no time). I would advise you to copy it in external, so that you'll be able to modify the code if you want and if I modify the code on my side, I can do a PR to you :).

Feedbacks and contributors are welcome. If you really find it interesting, I can make a quick doc.