Jan Vroonhof <vroonhof(a)math.ethz.ch&gt; writes: I have no idea. I vaguely remember it being intentional. There are definitely problems with the implementation. That wouldn't hurt. If you can get it done soon enough it can go into 21.0. I don't know. The Roman Numeral editor does it. File locking is unreliable over NFS. IMO it's safer to not use it. The current code will detect when a file has changed out from under the editor and that's the best we can hope for in the general case.