I also need zoom levels between 135% and 200%. Something like 150%. Having it user customizable would be great.

2 Row mode will not work for me because I have two instances of Total Mix open, side by side, on a 21:9 monitor. One for a UFX II and the other for a Digiface.

Customizable zoom level would be a godsend – I agree with gl, 135% is too small on a 4K monitor but 200% is too big. Unfortunately adjusting the resolution of your monitor isn't a viable workaround if you use your computer for more than just TotalMix FX.

I totally understand there may be technical limitations dictating the pre-set zoom levels for the foreseeable future (it looks like they had to be pre-baked into the app bundle), but I hope one day TotalMix FX's UI will be rendered as vector graphics like DigiCheck NG so it will be more freely resizable and scalable.

You could use the OS version and show only the options available to that OS.
You can assume old versions only run in old hardware. That is true for Mac OS for sure and mostly for windows.
In the end you have 3 driver versions per OS, Conditional compilation to the rescue.

Or a much more simple... 1 line of code:
Msgbox "Please note this mode might not work in your hardware use at your own risk" (don't forger the don't show again tick!)

I understand (and admire) your dedication to allow users to use old hardware. But providing a UI that also has 2024 look and feel is also possible.
I mean Soundcraft was able to do it in HTML5 years ago... resize the that browser and enjoy! Fits all resolutions in all devices with 1 single codebase :- )
I assume you use C++ so .. much more powerful than HTML5 ;- )

https://www.soundcraft.com/ui24-softwar … mixer.html