I notice on the Sandbox Forum, "Adios Dave's Garden" that the thread is marked [Done]. What does this mean? and how does it happen? I am not exactly opposed to the thread being [Done], but i am curious to know what this means. People continue to post on it so how can it be [Done]?

The person who started a thread in the sandbox can mark it as "Done" which does nothing except add that to the subject line.