This diff adds the option to blur the dab of the color smudge brush after placing the dab creating a smoother look.

It was originally conceived as a way to see if this changed whether mixes would be nicer, as this method is used in both clip studio and paint tool sai. It didn't, but I am placing this diff here so it may be tested.

Apply the diff, build krita, then in the color smudge brush, toggle 'blur dab' and lower the strength a litte.

The strength is the percentage of the brushsize that makes up the blur size. The sensors don't affect it, so I am wondering whether it doesn't make sense to replace these bits with a filter config as keeping the blur speedy is more of an absolute number thing...

This filter will have different effects depending on which smudging mode you use... either way, I think it's best people test it out for now, to decide if it's even worth including.