When using auto-completion on a textbox, and using the enter key instead of clicking the value to select a value in the drop-drown list, the onChange event is not triggered. That could make sense if it was when leaving the field, but it's not as well, I guess the browser thinks the value haven't changed since it is set via setting the value attribute directly on the input field, here is where it's happening:

YAHOO.widget.AutoComplete._updateValue (autocomplete-mi…:formatted:995)
YAHOO.widget.AutoComplete._selectItem (autocomplete-mi…formatted:1007)
YAHOO.widget.AutoComplete._onTextboxKeyDown (autocomplete-mi…formatted:1204)
n (event-min.js:7)

Setting @value doesn't trigger a change event, and leaving the field either.

This is a problem if we have validation as well using checkUrl or doCheck method, because the we can choose a value using enter, leave the field and the value will never be validated.