When you face directly into the "decal", it is so damn buggy. But not with this angulation...
Strange. I also tried to put the transparent walls but still nothing, it's glitching and flickering like a blockmixing gone bad...
For Information about this feature you might want to ask Toninus, he indeed was one of the very first to experiment with it :- ), here are two YouTube videos by Toninus, showing the feature: