fdo#73869 fix highlight RTL Problem at the StartCenter window.

Change-Id: I744d8f85c6e4c555ef8916281ebdc709fe6ddfa9
Reviewed-on: https://gerrit.libreoffice.org/7719
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>