for the area behind the slide, that is

Change-Id: Ie020f43a81e5eaa257c20d0a7b6feffce1614205
Reviewed-on: https://gerrit.libreoffice.org/16466Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Philippe Jung <phil.jung@free.fr>
(cherry picked from commit 1c481fe6)