container background TOP enhancement

I’ve done image selectors in UIs a ton of different ways, and where I’ve mostly landed these days is to fill either a cache TOP, or texture array then use a cache select or little GLSL shader to extract the slice I want, then set that as the BG. That, however, can be a lot of extra operators.

What if instead the Background TOP parameter had an additional par for slice or cache depth if a 2D array or cahce TOP was used as the input?

That would sure be swell and save some ops.