[rhelv6-list] info on 6.1 and online resize of virtual disks

[Gianluca Cecchi]

Hello,
on RH EL 6.1 release notes doc I can read this (page 11):
Virtual disk online dynamic resize feature

But in my rh el 6.0, after updating it to 6.1 and reboot, I cannot see
how to use it, at least in virt-manager app.
Neither in virtualization manual I can see related information..
Is this an error inside release notes document or do I have to use
virsh command or what?
Thanks in advance,
Gianluca