Show current (inherited) access rights
Currently there is no simple way to see which access rights are valid for a single file or folder.
You just see that there is nothing set at this file/folder.
How about show inherited rights as (non changeable gray text/items) in the mask?
So 'Advanced->Acces rights ...' would show the current state (black for set here and gray for inherited).
This would help a lot on finding problems, like I can't do this or that.