Zero-thickness/invisible displays could be overlaid on top of any other block of my choosing, including the in-game computer screens, so I would not really need a slab version. That would not help in cases where one wants to put a display as a slab, such as over the top of a control panel, but I'd be content with an active computer screen set on the wall behind the console.
Keep in mind that in a voxel game, only one block per "space cube" (tm), but that wouldn't stop Schine from, say, turning the display into some sort of decal object, allowing the display to be plastered on any surface, whether it be one of the angled blocks, a slab of tekt, or anything else. Then that voxel could have special exception handling where, no matter the underlying block, it suddenly acts like the good ole' display block.