Also, Ctrl-Z in Opera also works, which makes perfect sense and is less for the user to learn, and is discoverable (in the sense, they can go to the standard Ed

Also, Ctrl-Z in Opera also works, which makes perfect sense and is less for the user to learn, and is discoverable (in the sense, they can go to the standard Edit -> Undo menu which is more visible.) Although actually, Opera also has a visible basket of closed tabs on the right of the tab bar, which is even better.