Multiple view using differents rights

[Erwan Velu]

I've been trying realvnc, it works pretty good.
I can connect two java client at the same time on the same screen, this 
is nice.
I was wondering how can I define "profiles" to my users, I mean I'd like 
to have several roles:
- active
- passive

The active ones, may connect the session and interact with the 
keyboard/mouse,
The passive ones can't interract, they are just "looking at the screen".

So I'd like to have a user "admin" and a user "demo" that look at the 
same screen but with different rights.

Is there any possibility to achieve that ?