We run events where the registration is handled via an offsite link. I can disable registration and link using html, but it places a "We are no longer accept registration for this event" message. I can hide the message but there are some events where we do close registrations and the message is valid.
We also have some events that are not ticketed and are really just Calendar entries - it would be nice to customize the 'not accepting registration...' message on a per event basis.
