I was reviewing a post and had typed half a comment. The grey bar with "this post was edited -- click here to reload" or similar popped up. I clicked it. The changes loaded fine, but my half-written comment disappeared and the add comment link now does nothing when clicked. (Not disabled; simply had no effect.)
Refreshing the page restored the link's functionality, but I still lost my comment text. :<
Low priority, I know; just putting this out there.