how to switch vm console to/from read only mode?

hi,
is there any way to put the browser-vnc console in read only mode?
sometime i need to be able to look what a user is doing without interfering with its activity (mouse pointer)

before you ask, no i'm not spying users, its an external tech support for a commercial app that often needs to work an a windows server (btw via the "supremo" remote control app). i just wish to be able to check what he's doing, in case something goes wrong. sometimes he asks me to act locally (because it's faster) so i need to be able to switch back to interactive mode, too. i think it's possible with the regular vnc client too.

any ideas? is this regulated by a "monitor" option or else?

Thanks, Marco

pve-manager/2.1/f9b0f63a
root@pve2:~# pveversion -v
pve-manager: 2.1-1 (pve-manager/2.1/f9b0f63a)
running kernel: 2.6.32-11-pve
proxmox-ve-2.6.32: 2.0-66
pve-kernel-2.6.32-11-pve: 2.6.32-66
lvm2: 2.02.95-1pve2
clvm: 2.02.95-1pve2
corosync-pve: 1.4.3-1
openais-pve: 1.1.4-2
libqb: 0.10.1-2
redhat-cluster-pve: 3.1.8-3
resource-agents-pve: 3.9.2-3
fence-agents-pve: 3.1.7-2
pve-cluster: 1.0-26
qemu-server: 2.0-39
pve-firmware: 1.0-16
libpve-common-perl: 1.0-27
libpve-access-control: 1.0-21
libpve-storage-perl: 2.0-18
vncterm: 1.0-2
vzctl: 3.0.30-2pve5
vzprocps: 2.0.11-2
vzquota: 3.0.12-3
pve-qemu-kvm: 1.0-9
ksm-control-daemon: 1.1-1