KDE is an international technology team creating user-friendly free and open source software for desktop and portable computing. KDE's software runs on GNU/Linux, BSD and other operating systems, including Windows.
With KDE you could set Meta + Scroll wheel to adjust window transparency, you can do that in the section of the settings where Meta + drag is set for moving windows, don't remember what it's called
Edit: Just turned on my PC and checked, it's in settings under Window Management > Window Behaviour > Window Actions. Set the bottom mouse wheel option to "Change opacity".
Meta is the "Windows key" if you didn't know
This is absolutely brilliant. Thank you! This is massively helpful.
You could use a window rule.
Thank you. I appreciate it.
I don't really understand what you are trying to accomplish, but kinda sounds like you're looking for a way to make your 3D model match the dimensions of the actual IRL part. You would need to use some kind of CAD software to do this, or for basic scaling you can measure and resize your model in the slicer.
I understand it's an odd request. I'm testing an OpenCV app I'm working on and want to be able to match the perspective as close to identical as possible as part of some testing. It only took a couple of minutes, after learning how to adjust window opacity.
If I understand what you're asking, and if it's still needed, maybe there's some transparent theme you can add through Kvantum?