You have a good style I have to say. Please post more of your paintings
@fateline-alpha, @Boris Eyrich:
As for the request - I'd attach mine to it (as it really lies along the same lines) because there's even better option available. When you pick the underlaying colour you actually partially merge it with the layer, and when you remove the underlaying layer you'll have remaining parts of it at the top layer.
Personally I treat the new layer as the thing that you put on top of the 'dry paining'. As the result of this thinking is an idea to pick up the transparency. So if you'd be using brush like wrap, smudge or with high bleed it would cause the paint + alpha layer + impasto layer! to shift around.
For example a brush with 80% bleed and 80% opacity (let's omit other ingredients for a while) is used on the transparent layer then dab paints (0.8 * 0.8 = 0.64 transparency + 0.36 * colour) x dab mask (if it finds the 0-level of impasto it paints (0-level impasto in 0.64 strength + 0.36 * required impasto strength value) x dab mask). Also transparency lock icon would be highly useful to me.
Actually there's a place for the 3 methods (the current one, the fateline-alpha's idea, and mine feature request) in the same painting algorithm. If you're interested in example videos about how this feature could work, or help with developing dab formula just PM or email me. Not sure if we didn't talk about it already in the past but not in that details.