Tested it with that jerk sdfadsf. I like this better than the prior iteration though that offered more flexibility. Works well here on Safari on Mac. I like that the X shows up right over the prior icon without anything shifting around.

If I'm hunting for criticism, I would say maybe reconsider using the downward arrow when it is not being hovered over. Perhaps instead a same-gray-colored X? Or is the idea that it could be a drop-down?

If I recall correctly, you can still see that a comment was made from ignored commenters, meaning that the On Ignore list isn't strictly needed

I see "On Ignore: Alter, CK MacLeod, undefined", but I don't see the headings for any comments of theirs, so I assume I'm the only commenter here so far

here's a comment