When I'm writing a comment on skeptics.se, it takes a lot of time to create it and fix it and I use all the characters allowed that it looks like a small paragraph.
Usually you have to link studies, and academic articles, etc...
Many times, my browser went back automatically when pressing backspace (to delete something), and (on my macbook if you slide two fingers on the left of the pad, it will go back), it is really annoying and it happened with me many times.
The comment will be ereased and I would have to re-write it again.
You haven't posted your comment yet, are you sure you want to navigate away from this page?
when trying to navigate away from a page with an unposted comment.