Chosenbox aria-activedescendant out of sync (za11y.jar)

Steps to Reproduce

<zk>
    <zscript><![CDATA[
        ListModelList model = new ListModelList(new String[] {
            "aaa1", "aaa2", "aaa3", "bbb4", "bbb5", "bbb6", "ccc7", "ccc8", "ccc9"});
    ]]></zscript>
    <chosenbox width="500px" model="${model}"/>
</zk>

type "b" to filter only the items starting with "b"

Current Result

the aria-activedescendant is pointing to the last item in the list ('ccc9')

Expected Result

the aria-activedescendant should point to the currently highlighted item in the list ('bbb4')

Debug Information

Workaround

the patch in ZK-4819 also covers this issue