I've actually some nontrivial progress on xi-win in the past month or two. I still consider it experimental, but it offers basic editing functionality now. It's written basically directly on top of winapi, no toolkits or frameworks, which I'm doing partly because I enjoy tinkering, and partly because I expect to be able to achieve significantly better performance than would otherwise be possible.

Syntax highlighting is not working, largely because I can't figure out how to compile onig. But we'll figure that out one way or another (if it's too hard, we'll switch to fancy-regex, which is pure Rust).