NAK from my side. Prof-Gnome might be an improvement over adwaita but it's still a bad default theme in my view. Everyone is free to chose a theme to their liking but the default theme should integrate into the target platform. I hate all those GTK apps on windows that look like alien.
That said, I don't use Windows, I only start Geany their for testing specific issues. So in the end of the day I won't block this becuase it doesn't affect *me*. I just don't agree with this PR and IMO it's the wrong direction for Geany on Windows.