I have two machines, both running Ubuntu 10.
Inner right and outer right monitors are server. Outer left and inner left are client.
Mouse works fine on both right monitors and inner left monitor. At the edge of Inner Left, the mouse freezes but is clearly registered on the Outer Left monitor because mouseOver behaviours are visible. This remains until I click or move the mouse back to the Inner Left monitor.
Once the mouse is on the Outer left monitor, the same problem exists when leaving the the Outer Left monitor. The interesting behaviour when going East is that the mouse will appear fine on the Inner Right monitor if I move at least the 1680 pixels needed to fully skip the Inner Left monitor.
Keyboard works fine.