Current size of Maildir folder

[juan_enciso]

Hi folks;

I have turn on qmail-1.03 + vpopmail-4.9.10 + sqwebmail-2.0.0
I need that sqwebmail show me the current size of my Maildir folder
for each users
It is need because my users have configured a quota size.
and It need know their actually size of Maildir folder .. 

How can add this function ? 

I can see the file .current-size into each Maildir folder,
Is It the number to display ? 

Please
any idea for this problem?? 

Thanks 

P.S.
Sorry for my english