Leaving a comment on a review jumps the viewport to a comment editor at the top, then jumps back down to wherever the user was. Instead, it would be better if non-inline comments were composed in a popup modal, then on save, shown wherever they ought to be without necessarily moving the viewport. If we want to display overall comments at the top and file comments near the file header*, fine, but if the user's viewport is below where any of the comment would render, don't moved it to view the comment. I think if what they're commenting on is in the viewport, go ahead and render it where it should go and move the content below it to accommodate. But if the what they're commenting on is even one line above the viewport, it should push the content above it higher and avoid pushing the content below it lower. Conversely, a target just below the viewport should push content below it lower without moving anything above it.
*#10 is about making the file divider more like a sticky header. The comments might go under that header, but they would not be sticky.