Perhaps by now it has been addressed somehow, but at min 18:55, to solve the issue of when user tabs to null after adding new value in helper form, then presses Set & Close button, we could message box "No value selected. Please select existing value from list, or type a new value and select it" to redirect the user to choose a value. Maybe a status box would be useful to instruct the user from the beginning to "Please select existing value from list, or type a new value and select it".