[PATCH dummy] fix pointer limits when resizing v2

[Eric Engestrom]

On Thu, May 05, 2016 at 01:07:26PM +0700, Antoine Martin wrote:
> Pointer events are clipped to the original screen dimensions with the
> dummy driver when using RandR to switch to a higher resolution at
> runtime. This fixes it.

Please use `git send-email` [1] to send patches, and add the quoted
text to the commit message.

Cheers,
  Eric

[1] https://git-scm.com/docs/git-send-email