This was requested and talked about before, but here goes again. Spare Channels don't behave as simple additional alpha channels. When I create a new Spare Channel, specially if it is created out of a color channel, I expect it to behave just like a color channel, except that it describes "luminosity" or "opacity/transparency" information. But I assume I could still use all painting/editing tools on it. Stuff like brush, dodge, burn, smear, blur, etc. Also, Levels, Curves, Brightness/Co