Enhancement - Track Changes for undo

[nickzuber]

We should track changes for an "undo" option. This should be pretty easy with the system already implemented — just store previous states. Since we removed the update throttle, we have to be a bit more strategic here.

[nickzuber]

Would be interesting to add — something to note is that we can't just simply hook in the text state to some history system unless we wanted each Cmd-z to trace each letter