Okay, looking about there's a few places where we could want dithering to improve gradients, all of these should be optional:
- Displayfilter, so that people have the feeling 16bit and higher is indeed as smooth as a babies butt.
- Gradients, primarily for drawing 8bit gradients.
- Converting from high bitdepths to 8bit
- Brush masks... aparantly the brushmasks currently give odd banding artefacts: https://forum.kde.org/viewtopic.php?f=288&t=132097&p=354832#p354832 dithering could deal with this.