Limiting number of sessions for clients

Hi,

I'm having problem with users occupying all avaible sessions (set with
limit) when they uploads a lot of files in parallell.

So my guestion is: is there a way to configure wu-ftpd to limit the
number (parallell) sessions for a certain client. I have tried
file-limit but it does not work as I expect (or wish). 

Thanks
Mats Jakobsson