When you switch tab the current row/col header needs to be
invalidated.

Change-Id: I26ef6f9990726f3c96ddfc9ac45472fafc8e8507
Reviewed-on: https://gerrit.libreoffice.org/37242Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Jan Holesovsky <kendy@collabora.com>