This is a request to LOCK discussion thread in a task.
Even 'Completed', tasks sometime keep going: people continue write there being notified post by post.
Would be very helpful to have LOCK button, in order to keep all informed that current task is over. Kind of 'read only' option: post field turns grey and doesn't allow to type in.
LOCK button shall be available to Owners of the project. Or to those who has administration rights.