xfce 4.6: log out -> switch user

[Mihamina (R12y) Rakotomandimby]

Hi all,
On my fresh 4.6 (from Xubuntu Jaunty), there is no "switch user" button 
when loggin out.
Would you know how to get it?
I often "switch user" with my wife and loggin out is quite uncomfortable 
as long as I have tons of opened apps...
(I use a Phenom Quad with 8GB of RAM, just for the purpose to have tons 
of apps opened)