So a view can be aware where selections of other views are.

Change-Id: I5026b1ff2b99a4eedfd0bde32a05ceb8e2f424bc
Reviewed-on: https://gerrit.libreoffice.org/26542Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Jenkins <ci@libreoffice.org>