I don't know, but I would check the API of the SO you are under, and see how the FileReference is implemented and how to call the API method.
With some luck, it has already been implemented.
- [Pharo-users] How can I know if a file is being written by... Sebastian Tleye
- Re: [Pharo-users] How can I know if a file is being w... Sergio Fedi
