I thought I'd recreated the scenario you described at the start of the thread which I understand to be:
1. A normal X server running on the linux host (device 0) this provides the normal console display on the linux host, keyboard and mouse inputs.
2. The xinit starts the Xvnc (tightvncserver) running as an Xserver (device 1) on the linux host with vnc output to a vncviewer (Kindle or PC).
3. x2vnc then forwards the mouse (and keyboard) to device 1 when the mouse goes off the desktop of device 0, e.g. the East boundary.
In my case both the native X and Xvnc servers work on the Pi. The vnc viewer connects to the Xvnc server. The x2vnc appears to connect to the Xvnc server and the cursor does go off the East boundary.
It appears the last part, the x2vnc forwarding display to thr Xvnc server does not appear to be working.
Also if I use a Windows PC as the viewer rather than the Kindle the Xvnc server responds to mouse control from the PC. Is this normal behaviour or should the x2vnc lockout other mouse input to the Xvnc server?
It could be an x2vnc problem but I was looking for verification that the configuration was "correct" and any tips on diagnosing the x2vnc to validate of that's where the problem is.