PiP protocol addition...!?

X11 was certainly not without its issues that, depending on the specific time in history oscillated between somehow bothering and really very bad. Most of the issues that I have historically encountered was with hardware support, though. I still remember the frustration with a laptop where small portions of letters on the terminal were erratically not printed due to some 2D acceleration issue. Today hardware support is generally sufficiently good, so maybe I notice other things more.

Or maybe I notice them more because the solution _seems_ easy (agreeing on a single env variable) and evidently it is not.