Brilliant!
Emanuele Tamponi (Thrain) has managed to implement Kubelka-Monk color mixing for Krita's mixer palette. This means, simply put, that mixing works like in real life. It uses the reflectancy of pigments to reliably mix color on the computer and get the results you've been taught in primary school.
This is really unique. There is no other software available that does this. Corel Painter doesn't do this. Photoshop doesn't do this. There are some academic experiments that do this -- but it's impossible to get the code or the binaries for that.
Hip hip for Emanuele!
(Pics will follow when I've either compiled Krita (I broke my tree) or have finished moving house, whichever comes first.)