no warning in glade about it, though there is for other
such things that don't exist in the targetted version

Change-Id: Ib1522aaf9709b94274db378678314dc945048d97
Reviewed-on: https://gerrit.libreoffice.org/60899
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>