Yes the mechanics I'm familiar with, but never figured out the logic or purpose. Don't understand what the "picked" color actually does. Seems that if I go +100 saturation, it will mix any colors selected by the brush with the color picked, producing a third new color (i.e. selected green with brush, picked red with picker, get orange as a result at +100 saturation). If I go -100 saturation, the area selected by the brush becomes the color picked, or rather close-ish, it's still not quite that picked color. I couldn't find use for that. Probably doing something wrong.
Thanks.