Just a quick note to point out a bug (?) I found today while working with the ActionScript 3 Text Layout Framework.
I wanted to add a mask to the Sprite container I’d passed to my TLF ContainerController. Whatever it is that happened wasn’t correct: there was masking occurring, but the shape I was using as a mask was (incorrectly) visible on the stage. Rolling over my buttons caused redraw of stage regions, and my TLF text in those areas would go from invisible to incorrectly masked.
After trying several things, I pulled an old-school trick out of my bag: nest the Sprite I was passing as a container to the ContainerController in another holder Sprite, and apply the mask to the holder instead. From there, everything worked as expected.
Note: I further tracked this down to be caused by the ContainerController being created smaller than the text stuffed inside. Only then do I have problems with masking. YMMV.