A most insensitive and useless message box

Has this happened to you? From Facebook (or any other website), you're trying to jump to another page and this window pops up asking "Are you sure you want to leave this page? Your message is still being sent. Are you sure you want to leave?"

You can't proceed because you probably accidentally pressed the spacebar on the reply box of a friend's status message and now the browser thinks it's an unfinished message. But you can't find where that "unfinished message" is, unless you scroll all the way down and scrutinize each box (and what if it's a blank space or a tiny period?).

Microsoft calls this a modal box. It's a window that won't allow you to do anything else until you select the only options presented to you (in this case, stay or leave -- but have that nagging sensation that you've probably left a reply unsent). Modal boxes are frustrating, actually, though trying to be helpful.

In Gmail, this is a useful message because you are only dealing with one message at a time and if it pops up, you just go back to that message. But in Facebook, you'd have to be really patient, or just click "Leave Page".

Stepping back, you realize that this popup is a useless box. Why? You can't do much to rectify your error. It just reminded you and gave you one more little thing to worry about.

How can we improve this message? Maybe it should have a link that jumps you back to the unfinished message. Then we won't have to gnash our teeth.