Hiding area should remove navigation as well

[MichaelKohler]

Is your feature request related to a problem? Please describe.
When I remove the agenda from the template, the navigation item at the top is still there and then doesn't point anywhere anymore. This needs me to remember to remove it. See https://testforbug2.splashthat.com/ for an example.

Describe the solution you'd like
It would be great if when hiding a block, the navigation item at the top would be removed as well.