(Note: this post concerns a moderator-only ability.)
Moderators can undelete comments. I mostly find this useful when there are a lot of obsolete comments on a post: I use the “purge all comments” tool, then I want to undelete the couple of comments that should stay.
… And I can never remember how to do it, because the solution is to click on some very faint text that appears in the left margin of the page. With a normal window width, this text isn't visible at all! I need to widen my window to 1251 pixels to see the box at all (but truncated on the left), and to about 1300 pixels to see the box in full.
Please make comment undeletion more accessible. It should be on the comment view (“show N deleted comments” mod tool).
More generally, please don't hide UI elements by putting them outside the window. If it's worth having at all, it's worth having where we can see it and click it.