Thanks again. I think I own just about every Imagineer product except Mocha Pro. I have Mokey ( build 4.1.4 BTW), Monet, Mocha that came with CS5, and an old version of Motor. Are you saying that Mocha Pro can be used like Mokey as a remove tool? Trouble is, even if that's true, it means owning Mokey is a waste if I have to buy yet another product.
Anyway, I don't think it's necessary to send you a file if I describe what I'm trying to do... Imagine an object like, say, a ball with an intricate pattern on it. I want to remove the lefthand side of this ball and reveal the background behind it. But... the ball is travelling from left to right. If I roto out the lefthand side of the ball, but follow the intricate pattern on the surface of the ball (say to follow a logo) using the weight (curve) controls, if I just leave it at that, the righthand side of the ball will leave a trail of its lefthand edge in the area of the remove as it tracks to the right. So, I need to tell Mokey not to use any of the pixels from the righthand side of the ball. By attaching the two layers, this works really well. If I just overlap them, the righthand side still leaves a trail from the overlap.
But here's the problem... while attaching the two layers works the way I want it to, if I attach a newly created righthand layer to mask out the righthand side pixels, it trashes the carefully created curve of the original roto. So I'd really need to do the attach up front. That's a problem because of the complexity of the roto'd shape. It's much easier to do the roto first and finesse it before creating the next mask layer. Or so I thought until coming across this issue. I just didn't suspect it would trash the curve and reset it to maximum sharpness (pointiness). So now I either start again and hope I don't screw it up, or grin and bear it and readjust each weight control in every keyframe.
So the problem is easy to reproduce. Just create an object and create a roto through it that has the weight controls adjusted to give it a curvy profile. Then create and attach another layer to the dividing edge and watch the weight controls reset to max sharpness. For this test, you don't need to worry about the contents of the frames. Maybe there's a way around this that I haven't thought of.
Cheers - Mike.