I know what you mean about the brushes. What I did was make a brush, then make a mask for the brush and fill it in with white. I did several of these on a grid then saved it as a single layer with a transparent background. I then imported the image into Paintshop Pro and exported it as a picture tube. This meant I could paint with the mountains and the 'white' areas remained solid, thus covering up anything they were over lapping.
That sounds promising. Gotta try that.
As for the "mountain thread": I was talking about this one right here! I liked your mountains a lot I saw them the first time but had forgotten what this thread was called!