Neo2 layers support

[Atemu]

I just now found out HK supports neo2 which is great news.

However, the upper neo layers are emulated via the long-press menu which is fine but can get a bit fiddly and isn't 100% complete either. (Some keybinds also wouldn't make sense as popups, e.g. arrow keys, esc, enter, insert)

There is something similar to a layer in the Fn menu, is it possible to add more of those and if so, where would you start?

Would adding the two additional mod keys pose a problem? (Other than even more screen real-estate problems of course)

cc @fahrstuhl

[fahrstuhl]

Sorry, I have no idea how to add layers. It's been forever that I looked at the Neo implementation in hackerskeyboard. (I think some of the alt characters are missing because they can't be displayed? I remember putting all of them into the config.)