Grant Create rights, but not visibility rights?

With the simplified rights in Filr, is it possible to share a folder with create, but not file scan/view rights? My thought is that I'd like to allow a teacher to share a "turn in" folder with students, so the students can add upload a file to it, but not see the contents (and what others have created in the folder)?

Also, can I allow them to create files, but not delete them?

This simplified rights model seems like a bad idea to me; is it written in stone, or is there a chance it will ever change/expand?