you can use root password to login in user panel
I always use root, but FTP account manager only works with single user, not root.
So i have to login as "user" with user password to being able create a new ftp account.
Maybe i don't understand you.
Also tried to use "user's" domain using root, but the result is same than login root over IP address so the only diference is that root has NO customer panel, so you must create at least one user to use "users panel", wich is the only panel that allow you create FTP accounts.
Instead of the root being able to edit all acoounts, root can edit none of them.