continues the work of Sharpness brush option rework
Strengh controls how much sharpness is applied to the pixel data:
Soft controls the edge grays gradation.
Soft Edge acts on the non sharpened edges. If Sharpen strenght is set to 100, Soft will apper to do nothing, Soft Edge is more designed to fine tune the amount of transparent pixels. The difference with Strenght is that, Strenght clips to black from opacity and Softness clips to transparent pixels from alpha value.
Default behavior: Strengh 100%, soft 0 (this is the old behaviour)