detecting dark/light OS settings and following them

It's nice to be able to change the app's theme, but it would be even nicer later (after the hard fork) to have the app blend in automatically.

For windows I have found these: https://godoc.org/golang.org/x/sys/windows/registry https://stackoverflow.com/a/58494769/14378916 a registry access library and info about which key to read.

There will be a way to do this with at least gnome, iOS and macOS as well. I think this doesn't exist on android until 9 or 10.