Steps to Reproduce

<zk>
    <zscript><![CDATA[
        List locales = new ArrayList();
        for(Locale loc : Locale.getAvailableLocales()) {
            locales.add(loc.getDisplayName().toLowerCase());
        }
        SimpleListModel model = new SimpleListModel(locales);
    ]]></zscript>
    <combobox model="${model}" autodrop="true" instantSelect="false"/>
</zk>

1) type "eng"
2) then use UP DOWN keys to browse the available selections (don't select yet)
(use varying intervals between UP DOWN keystrokes)

Current Result

at some point the selection will trigger even without pressing ENTER
the list of choices will be reduced to a single comboitem

Expected Result

same as with instantSelect="true"
-> don't reduce the choices unless more character are typed

Debug Information

in a working case UP/DOWN send an onChanging event with the flag bySelectBack=true (resulting in an empty AuResponse)

in the failing case the onChanging event is missing this flag (then the response contains updated comboitems)

Workaround