The reported maximum was wrong. The X and Y coordinates are 0-based
so if size is 8000 maximum must be 7FFF.

Signed-off-by: Ladi Prosek <lprosek@redhat.com>
Message-id: 1460128893-10244-1-git-send-email-lprosek@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>