Man, I really hope they update to support 4k monitors in Win10 when they release Native. I just attached my Win10 laptop to a 4k monitor and immediately came across this issue and came here looking for help. What's weird is that they support retina fine on macOS, which I know handles this stuff better than Windows, but it's totally doable in Windows if the developer cares enough. I really hope they get this fixed, the app is unusable right now :(