Xen 4.1.2 with pygrub gpt patches back ported installed on top of Ubuntu 11.10. Virt-install'ed  F16 PV guest.  After domain gets created VNC login screen shows up. Mouse should be kept always inside VNC screen.  Otherwise , it will disappear. Start F16 domU  via virsh and connection via vncviewer gives working mouse pointer, which looks like "dot"  in VNC session, but gets grabbed. Boris.