Keymap was from my own port for the M6-A before official support was added, thus the backlighting code is not ported yet from the official default keymap.
Top-right button acts as a "toggle between layers" button. Layer 0 -> Layer 1 -> Layer 2 -> Layer 0 -> ...
Use [karabiner-elements](https://github.com/tekezo/Karabiner-Elements) on macOS so that the state of the modifiers (shift, caps lock) are synchronised between keyboards (for shift + arrow key text selection, for example). It's also a handy tool for customising keyboard behaviour on a Mac.
On Windows/Linux modifier state should be shared between all keyboards by default.
Installation: install [homebrew](https://brew.sh) and run `brew install Caskroom/cask/karabiner-elements`.
