An UNDO Option would Really be Useful
However - one other Glaring Omission is this.
There is an ADD Option - but guess What ?
There is NO Delete Option.
If you accidentally added something you did not mean to - and only noticed it a little later - how the heell do you get rid of it ??
The Undo would undo everything in the last step - even if you stepped back to when you added the thing yo did not want, you would LOSE everything you added since.
Please, Please - Add these Options