Canvas is a great tool for composing email campaigns. We are getting slightly paranoid about overwriting each other's work, however – that's happened before when multiple editors were working on a campaign at the same time.
Could CM have some sort of an alert/indicator whenever another editor has the campaign open elsewhere?
At this point we don't really have a way to handle multiple editors at this time, but we do have a request for this in our system, and I've just added a vote on your behalf for a better way to handle this. We'll be sure to write back if this is something we do in the future! :)