Would it be possible to share a folder when you have "read only" permissions ?
I think it would be a very interesting feature. Maybe it could be set when assigning "user" / "Permission" to a specific folder and follow the same strategy, change the ability to a user when you want.
The use case could be the following; Imagine you have alll your music folder. The master copy is shared (owner privileges) with laptop and home pc, then you have your mobile, the sharing is "read only" privileges and "selective sync". Then you are with a friend, you have your mobile with you and you want to re-share with him / her your music library (of course with "read only" permissions)