THANK YOU FOR DEC 6th 2017 UPDATE!
Oh happy day!
Creating categories on the fly has been a long time coming - so excited it is functional!
"You can now create new categories while adding transactions. You used to have to abandon your nascent transaction, go to your budget, create your new category, then go back to adding your transaction. Not exactly frictionless budgeting. Now you can add the category right from the register."