MR diff comment box always appears on the left in side-by-side view

The Problem

In the attached screenshot, I'm attempting to add a comment to the code additions in the right side panel:

It's somewhat counterintuitive; I immediately thought I was writing my feedback on the wrong snippet.

A light proposal

Regardless of which line-number column I click on, left (old state) or right (new state), the comment box appears on the left half, as if I'm commenting on the old state. I suspect there is no such thing as commenting on one or the other, and the comment I'm writing will be attached to the combined diff. A quick look at the multi-line selection menu in the comment seems to confirm this:

If that's the case, we should probably have the comment text box span both columns, and maybe have the mouseover-highlight-and-speech-bubble-icon applied to both sides of the diff at once, to imply that a comment is being added to the entire diff at once.

A wilder proposal

Can we support attaching comments to the after-state diff or before-state diff separately? It does make some sense to me that a reviewier would want to comment on one of them specifically, to say something like "a thought on removing this" or "a thought on this piece that's been added in". But I don't really know how the mechanics of code diffs and attached comments work, so this might require an unworkable redesigning of diff comments.