[PATCH 3/4] protocol: Introduce pointer_lock interface

[Bill Spitzak]

The pointer lock is a one-shot (ie on exit and enter the pointer is not 
locked again), right?

Kristian Høgsberg wrote:
> The pointer_lock interface is modelled after the HTML5 pointer lock
> extension:

> +    <request name="lock_pointer" since="2">
> +      <description summary="return pointer object">
> +	The lock_pointer request lets the client disable pointer
> +	motion and request relative motion events.
> +
> +	This request initializes the pointer lock and activates it in
> +	case the surface is active.  If the surface isn't active when
> +	the server receives the request, the compositor will activate
> +	the pointer_lock when the surface is eventually activated.