There needs to be way for a client to lock the pointer to its window. A common use case is 3D games where the pointer is used control the viewport in a 3D space.
An RFC inspired by the corresponding W3C API was made in Februaray 2013: http://lists.freedesktop.org/archives/wayland-devel/2013-February/007635.html
A follow up to the previous RFC posted here: http://lists.freedesktop.org/archives/wayland-devel/2014-September/017318.html
I'm adding a depends-on to bug 85715 because that report raises an interesting question: with high-resolution, high-rate mice, can we still use wl_fixed_t for the relative motion events, or can it be too imprecise leading slow motion to be rounded to zero?
An unstable protocol (pointer constraints) was released as part of wayland-protocols 1.1. Weston 1.12 includes support. I'll leave this one open until there is a stable protocol added.
At this point we can probably close it ... :)