Posted Jun 15, 2012 3:53 UTC (Fri) by whot (subscriber, #50317)
[Link]
GNOME3 already uses this to block the movement of the pointer from the Activities menu (if placed on the right monitor) to the left monitor.
I believe Unity uses it in some way too, Chris Halse-Rogers has been working on the protocol to add threshold-based pointer barriers (if you move fast enough, you can push through a barrier).