While using AutocompleteExtender, we could notice where the other controls are been overridden and the autocomplete extender text being overlapped by the other controls near by.This could be overcome by calling the OnClientShown property of the AutocompleteExtender control.
<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>
