[BlueOnyx:13348] restrict access to subdirectories for FTP user

[Frank Soyer]

Dear list,
on a site maintained by more than one developer, we want to restrict FTP 
access to some directories for some of them.
For example, we want that the graphic designer can only access to 
/web/images and /web/upload, and never /web and / (even in R.O.). But 
the site administrator must have access to all directories.

If I create a user in the interface, giving him ftp access, his group is 
the site group and he has access to all the tree from /. Changing his 
group isn't a solution, he has no longer access to directories. Creating 
symlinks in his home dir doesn't solve either, if he can still change 
dir to / or /web.

Have you some idea for this ?

Thanks
Frank