I did test it! I had no VM with Windows 98 SE already installed, so instead I used someone's "Windows 98 Live CD" from the Internet Archive. I integrated hicolor.exe and some test pictures into the ISO with ISO Master and booted qemu-system-i386 from it. The program passed manual testing. I realized I could automate the ISO mastering with a shell script and the actual testing with a BAT file to create a Windows 9x approximation of fresh-VM CI without messing with HDD snapshots, but (somehow!) decided not to. I don't think I will be integrating Windows 98 SE or Windows 2000 into the CI pipeline, so support for either may break.

Awesome. Feeling nostalgia now :-D

Can you do this in a VM?

Yes, but the author is most likely using a Win API that is known to exist since that operating system & service pack. I doubt they tested every version, unless they are the curious type :)