I accidentally clicked on the "this is a great comment" up-arrow icon next to a comment on a Area51 proposed question and I want to undo this. On other SE site you simply click the icon again, but this doesn't work on Area51. Is this intentionally? Can this feature please be added?
That happens to me on occastion — the "oops, I didn't mean to press that" <click>. An undo-comment-vote feature was added to the main Q&A site early last year:
Unfortunately, the code that runs Area 51 was split off the main Stack Exchange code base long before that feature was added. It's not terribly likely (although not impossible) that we'll retrofit many of the newer features back into this site. Area 51 is slated for a complete re-design, and I'd rather leave the developers to complete more pressing projects so attention can be brought back here that much quicker with a more comprehensive development effort.