If createable is set to true in the chosenbox:

Try the following on your Demo-Website https://www.zkoss.org/zkdemo/combobox/chosenbox?search=chosenbox

1. Type in to "Ada" for Adam.
2. Select with "Key Down" Adam in the popup list and hit enter

Expected behavior: Adam will be selected and put into the chosenbox as selected instead of "Ada"
Actual behavior: The "Selection by key" is ignored and "Ada" is added to the chosenbox

Btw.: The selection by mouse, does work.