libvirt users - Jul 2013 - dual head with virt-manager, kvm, debian

Hi,

I  try to run a debian testing guest inside a debian stable host and would 
like to use both physical displays to show virtual displays of my guest.

Is this possible?

I tried setting the heads attribute in the domain xml as described here:
https://bugzilla.redhat.com/show_bug.cgi?id=885806#c1

I've tried virt-managers internal viewer, virt-viewer and spicy without any 
indication of a second display.

Regards, Thomas Koch