This is my hacky setup to add math characters to my keyboard layout, accesible via an AltGr key. The fifth layer for script characters isn't working for me right now. I'm not sure it was a good idea to begin with. The part that I hacked in is the "English (US, math symbols)" part. Search for that to see what I did. Install with install.sh. This overwrites system xkb files, which is bad. Don't use this is you are not me. My recollection is that per user configuration (i.e. .Xmodmap) does not play well with multiple layouts. TODO: move my compose sequence configuration into here.