Possible Duplicate:
Question history attributed changes to me that I didn't make
When I was editing this question today the OP came back an made an edit during the grace period (five minutes?) when revisions are not tracked.
When I saved my edits I noticed that I'd apparently overwritten his update (he had added a link to the version of jQuery Data Tables he was using).
The system didn't warn me that changes had been made presumably because this is only tracked using revision numbers. Maybe it should do this (i.e. by calculating a hash of the original post then creating a new hash before allowing me to save. Then check if anything changed by comparing the hashes if the revision number is still the same - like a belt an braces check)?