I discovered the ValidValuesBinding attribute and class just yesterday and I must say: great feature. It is not that programming comboboxes the "old" way was terribly complicated. But now we have a clear structure and it is much easier to understand.
I wrote some util class converting a map of keys and values into a ValidValuesBinding, optionally with an empty line. I think some functionality like this can be of general interest and could be added to the Enterprise client code. Maybe provide a method taking a map as argument... I can pass you the code if you want.