[im_down_w_otp]

I understand what you're getting at here, but it's also possible that this wasn't a directly pursued feature, and may have just naturally fallen out trivially from their display system's architecture & implementation as a by-product. If so, then the cost would be to exclude the capability explicitly.

[em-bee]

exactly, just like it would be rather easy to add to any compositor based system like it's common now on linux.