Fullscreen doesn't fill the entire screen if scaling in Windows is used

[Tasosgemah]

Description

Non-Windowed Fullscreen doesn't fill the entire screen if scaling in Windows is used and the resolution you want to use is non-native (for instance this is what i'm getting if i use 1080p resolution on my 4K TV)

Expected behavior

I expect the screen to be filled

Actual behavior

The screen isn't filled, like shown in the above picture

Steps to reproduce the bug

Set custom resolution to 1080p on a 4K screen. Use scaling (In Windows) to 150%. Run RetroArch.

Version/Commit

Version 1.9.6 but it was the same issue in older versions.

Environment information

Windows 10

[c0d3h4x0r]

I am able to independently repro this using the same repro steps and conditions.

My setup: RetroArch 1.17.0, Windows 11, NVidia RTX 3070 >> HDMI >> Vizio 4K UHD LCD TV

This is an extremely annoying problem when I try to host an online gaming session via Parsec, since the fullscreen resolution must be dropped to get a decent video stream through to connected Parsec clients elsewhere on the internet.

[c0d3h4x0r]

You can work around this problem for now by right-clicking on retroarch.exe in File Explorer, choosing Properties, going to the Compatibility tab, clicking "Change Settings for All Users", clicking "Change High DPI Settings", checking the box that says "Override high DPI scaling behavior", and setting the "Scaling performed by" dropbox to the value "System".