[feature request]in viewport A/B visual comparison

In games there could be the need to easely compare the result of 2 visual setups to see what you like the best.

I was doing a test and put a screenshot in paint and moved the paint window over the editor for comparison.It was inefficient and i feel quite dumb while doing it.This feature could be very usefull especially when making time of day setups or developing a new shader or even just replacing a material on a mesh.

A quite standard solution in vfx tools but never seen it in a game engine is A/B comparison line you can freely move over the viewport.

In editor cmay save the screen with a button and then toggle this visual bar to compare the saved screen with the actual viewport content.

This is a great suggestion! This could be very handy for a wide variety of developers.