Well, I've been fiddling with this effect and it seems it is buggy. After reading trough this thread, which has the same issue as I'm seeing
And not knowing the policy on thread necromancy on these here forums, I took the liberty of posting a new thread.
So here's what I'm seeing with for example three layers
[*:3pf9gigf]Layer 3, mask layer (using alpha it seems for visibility of what's underneath)[/*:m:3pf9gigf]
[*:3pf9gigf]Layer 2, which should peek trough[/*:m:3pf9gigf]
[*:3pf9gigf]Layer 1, which should be left alone has all kinds of pretty test box thingies on it [/*:m:3pf9gigf][/list:u:3pf9gigf]
All of the above works, well sometimes... I've seen it influence layer 1 as well. As I've read in the thread linked above, it seems the mask just outright refuses to update after moving/scrolling or even re-testing using debug all. Leaving trails and simply not updating the render at all. Checking "force own textures" as suggested in the thread, doesn't seem to do anything either.
So what's the deal, how is the Mask effect actually used. I REALLY need to have some kind of mask effect for something I'm working on.