"Done" instead of "Close"

With cloud computing becoming a common practice, users no longer have to worry about saving. Every change a user makes to a document automatically syncs to all their devices. Therefore when users close documents, they are truly just making the app go away, rather than deleting everything they worked on.

Since closing a document no longer implies that changes are "gone", the close button icon, could be switched to a check mark, meaning "done". It is a small change although it may be necessary for people to make more sense out of the evolving dynamic of closing/saving documents.