re:
>I just got a computer with an Nvidia card on it over here but I am not able to reproduce that selection behavior at all, it's working normally for me.

thx for looking into it Michael! Appreciate it.
Looking at your specs - are you sure you've been running it on an Nvidia GPU?
I've noticed that you have GTX750M which suggests a discrete GPU on an Optimus enabled laptop - which would default on Linux to intel card without a bit of trickery. And even if it was running proprietary driver it would require primus / bumblebee which sadly adds a bit of variables to the mix.

I've did a test on a friends laptop which has a discrete GPU as well (GTX 660M). With nouveau driver it worked. Haven't had a chance to try proprietary driver on this machine though - I was a tad afraid to mess it up (my friend wouldn't be happy about it :D ). Also I forgot to check whether it was X11 or Wayland session (as it was Fedora 28 it is quite huge chance it was Wayland) - which would add another variable :/ .

I did a test on both of my workstations though and with proprietary driver I'm seeing the same problem. There's one more thing I'll check - both are dual Xeon machines. While unlikely it adds to the mix I'd like to test it too. I think I've tested it in the past and ruled it out, but as it has been 2 or 3 years I might be wrong.

I've launched MoI in Wine with Xephyr (thx to Lutris) and in such setting all those highlights / selection windows / etc update correctly. But it is not usable - under Xephyr it is super slow.

Part of the reason I look forward to V4 with the API selection option in cfg - I have a bit of hopes that maybe with proper forced API and DXVK the issue will be gone without extra hassle.