Autocomplete extender in modal popup issue with solution

<cc1:AutoCompleteExtender ID="ace" runat="server" OnClientShown="ShowOptions">

</cc1:AutoCompleteExtender>

<script language="javascript" type="text/javascript">

    function ShowOptions(control, args) {

        control._completionListElement.style.zIndex = 10000001;

    }

</script>