editable combo box behaviour

I have an editable combo box, as I want users to be able to select a value from a value list or enter their own value. Selecting from the list works fine, but if you type a value and hit enter, the field is cleared. If you exit the field using tab the value is kept.

The combo box has a script attached to ‘onDataChange’ which is triggered by hitting enter, but it already thinks the field is empty.

I have tried this also in an editable combo box without a script atttached: the first time you hit enter nothing happens, the second time the field is cleared.

Is this expected behaviour?