When adding an OnChangeAjaxBehavior to an AutoCompleteTextField, onUpdate() doesn't fire when selecting an item from the autocomplete item list.
It is firing when using an AjaxFormComponentUpdatingBehavior.
wicket-autocomplete.js seems to be using the onchange event handler, which is cleared by Wicket.ChangeHandler.
Maybe obj.onchangeoriginal should be checked in first place in wicket-autocomplete.js
See this related discussion at SO for context: http://stackoverflow.com/q/8047769/851811