>That wasn't the criterion, which was "the best"
Yes. Making perfect transition animations for the software is a very hard task, which is totally useless in my opinion — transitions shouldn't be made for screenshots, it should be made for humans to understand what have changed, how did click influence the UI.
>So show your Kwin animation example
https://litter.catbox.moe/s6ahsjybdcfkvdi5.mp4
>explain how it's the best due to "human vision" compared to a transition without the weird stretches.
Simple: Nikita's file picker example tries hard to repaint in time, and that looks very weird, because it's both janky and not how the window usually repaints.
And the latter is what the human eye and human brain are consider weird. If the animation does not attempt to present the contents during the animation, but instead only acts as a transition from state 1 to state 2 using smooth (as in constant-FPS) action, it does it job better, even if it does not preserve or even present the real contents during the animation.
The example of it could be seen on many websites which show the web page elements templates during loading (elements are positioned on their places but don't have real data yet).
>And again, what features of "the human visual system" does white window exploit that makes it the best?
If you present crispy sharp, high-fps picture to the user, the brain would look for any animation deficiencies, nitpicks.
If you just hide the contents in some way (blur, no repaints, no data), the brain just won't try to find anything weird.