Limit FTP access to directories

In Virtualmin Pro when creating/editing and FTP (mail) user I have the field "Allow access to web directories" under "Other user permissions", but this cannot be used to limit FTP access to a certain sub directory. Although it states

"This shows all password-protected web directories configurable in the Protected Web Directories module, and allows you to select which ones this user will be granted access to using his login and password."

in the help popup, this does not seem to relate to FTP access restriction. All control panels have this feature to add an FTP user which is restricted to a certain directory. Why does VM (yet) not have this feature?