I used VNC desktops as a kind of collaboration server, as shared planning and pair programming environment for a long time. Now my latest iteration uses a KVM guest running Fedora 17 "Beefy Miracle", the Cinnamon desktop environment and an X11VNC server. The X11VNC server is automatically started with the desktop environment using the following command:
x11vnc -localhost -many -shared -display :0 -bg
My problem is that depending on the VNC client, the mouse pointer of the remote system which is shown through VNC is not synchronized to my client. I really need this, so I can see what my partner is doing on the desktop.
When using Vinagre 3.2.1 on Ubuntu Oneiric Ocelot (11.10) or Vinagre 126.96.36.199 on Debian Squeeze (6.0) and I don't have my local mouse pointer inside the VNC view, I cannot see the mouse pointer of my remote system, nor its movement. When using TightVNC on Windows 7, I can recognize a mouse pointer trace for very short amounts of time after moving the mouse, but it is not clearly visible. Using UltraVNC on Windows 7 the mouse pointer is clearly visible all the time.
With Gnome 2 I never had any problems with remote pointer synchronization, using exactly the same clients. I suspect this could have something to do with Cinnamon's dependency on 3D acceleration. On the other hand, it doesn't change anything to start Cinnamon's fallback environment Cinnamon 2D.
Update: Same effect when I use Gnome 3.