Ok, I have an titlebar which, minus the layer effects, is just a rectangle with a 15 px radius. In theory I should be able to make a second white layer, merge them, invert that and have a mask. When I put this into my theme it gets really funky, I think its because some pixels on the edge are the same as whats in the source image, but I'm not sure. What is a realiable way to make a mask? I've used this method before (Xia Mia, etc) and its fine.