Thinking of alternatives, I think that in Paint or Sculpt Mode, while the selection tools are active (old masks) the selected areas could be colored the same color as in Edit Mode, but with a color gradient, while when using painting tools or sculpture, a contour could delimit the selected areas by approximation, in the same way that Facesets are proposed.
S can be a good key to activate the selection tool (currently scale) or temporarily overlay the selection when hold.
5 Likes