fdo#76937 Improve organization and layout in Position tabs

Change-Id: I55e08db1c4c32d0e2a1def293d1d42abb6717cb0
Reviewed-on: https://gerrit.libreoffice.org/12520
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>