> So a few people requested this feature, and I started thinking about
> its implementation. Immediately I bumped into several issues that I'm
> not sure how to resolve, since I don't really understand how this will
> be used in Emacs.
Indeed, it's non-trivial. E.g. if it's used for things like "go up
N lines", then it's important to make sure that the notion of "visual
line" is exactly the same for the "go up N lines" command as it is for
the line-number display code.