Fixed Retina detection for mirrored monitors

[excitoon]

Progress on #53 (fixes some cases)

[drov0]

Hi ! Thanks for your contribution, I'm sorry I didn't catch the mss issue I don't own a mac. Is there a way to detect retina without calling a subprocess ? I'm not a big fan of calling external processes (because with some aliasing you could have the lib call a different binary and it's a security issue)

[excitoon]

@drov0 actually it's quite worse than that, you can have one Retina monitor and one regular. I guess you need to design an API for multi-monitor setups for a start 🤷‍♂️

[excitoon]

>>> import AppKit
>>> [(s.backingScaleFactor(), s.frame().size, s.frame().origin) for s in AppKit.NSScreen.screens()]
[(1.0, <CoreFoundation.CGSize width=3840.0 height=1080.0>, <CoreFoundation.CGPoint x=0.0 y=0.0>)]

I had to restart Python to get changes :( (however, the current solution has the same issue):

>>> import AppKit
>>> [(s.backingScaleFactor(), s.frame().size, s.frame().origin) for s in AppKit.NSScreen.screens()]
[(2.0, <CoreFoundation.CGSize width=1512.0 height=982.0>, <CoreFoundation.CGPoint x=0.0 y=0.0>)]

[excitoon]

https://stackoverflow.com/a/69637863

Basically, we need some approach how to integrate this code into the library, unfortunately.

[excitoon]

Personally, I would stick to polling separate processes, with Python or not (for example, you can have some manual update method).