This is because text in box is same colour as the background.
This is only an issue for Linux/KDE.
This change fixes this issue.

Change-Id: Icb908ace25c69fd2fb51f8f44082ca6b00f55c43
Reviewed-on: https://gerrit.libreoffice.org/55660Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>