I have come across this issue before and there is a work around with layer and morphing but a simple paint-to-subtool would be awesome -the painting would have it's own independent masking that is invisible or the paint thickness and shape becomes the masking data.. then press extract-from-color on the layers or masking panel or the extract area on the subtools panel. I realized that if I could take the paint from the layer I was working in and just extract directly rather than having to do a sloppy mask then extract I would save time not having to trace over a complex paint job and that I could completely cover the new subtool with the material & color I needed within a few key strokes.
Voting on Ideas
Vote for your favorite ideas by clicking on the up arrow.To undo an upvote, simply click the arrow again. This second click removes your vote.