Thanks. I confess that I didn't spot the FAQ down there. I've got a question, though: how is the tool supposed to enforce anything unless the destination is the source folder itself? Wouldn't it make more sense to specify a destination for the backup of the current code instead and let the cleaned-up source code remain in the main project directory?

That would be cool. But then, a question arises whether the physical size of all the backups should become a problem at some point?

I guess a "diff" would do for backup (with each execution of Guantanamo making a new subdirectory for the latest diff).

Something like this perhaps:

/src/java/com/foo/bar/...
/src/backups
/src/backups/1/com/foo/bar/Whiz.java.diff (this changed)
/src/backups/1/com/foo/bar/Bang.java.diff (me too)
/src/backups/2/com/foo/bar/Bang.java.diff (just 1 this time)
/src/backups/3/com/foo/bar/Bang.java.diff (me again)
...

Of course, this kind of functionality might lead to reinventing CVS and it might very well be better to just stick with the simple solution (write over the previous backup or let the backup directories pile up) until the size of the backups really becomes a problem.