This is a more significant issue on Windows as the only file system control over a file or directory is read-only. In other OSs, an admin could just CHMOD a file/dir (via the interface) and control it, but this would also affect other programs that have access to the files/dirs.
So, another solution: use FM2's build in security to control if a file ability to be manipulated by users.
The standard system (present in 1.0 and 2.0) allows each user to be limited (or not) in five ways: allow deleting, editing, writing, reading, and seeing. These settings are system-wide.
This new system will allow an individual directory or file to be limited in the above ways. The owner (the creator of the file) will have full control over the file, and the owner can limit other users' access to the file. It won't affect other programs, and admins will always have full access to the file, as well as the ability to change the permissions and the owner of the file/dir.