>>>When there's a reply to the message.
>>
>>So when the user hits 'Send', not 'Reply'.
>>
>>That means the reply can have non-updated text in it, from a previous version of the message being replied to.
>
>Easier to turn it off when a reply exists. Besides, whoever hit the reply button may change their mind and not hit the Send button.

I figured it was that way...I just was tinkering to see how it works (and you, Craig, and Doug oblidged by replying to my queries). If you are updating a message, and a reply comes in while you are making the edits, you get a big 'Sorry Charlie...a reply has shown up' when you hit send.