var dataRequested = false;
/*var searchText = 'введите первые буквы'; */
var ok = false;
function region_OnClientItemsRequesting(sender, eventArgs) {
    if (eventArgs.get_text().length == 0) {
        sender.hideDropDown();
        eventArgs.set_cancel(true);
        return;
    }

    var context = eventArgs.get_context();
    context["FilterString"] = eventArgs.get_text();
}

function region_OnClientItemsRequested(sender, eventArgs) {
    if (sender.get_items().get_count() == 0) {
        sender.hideDropDown();
    }
    else if (!dataRequested) {
        dataRequested = true;
        sender.showDropDown();
    }
}

function region_OnClientDropDownClosed(sender, eventArgs) {
    var items = sender.get_items().clear();
    dataRequested = false;
}

function region_OnClientItemsRequestFailedHandler(sender, eventArgs) {
    // set cancel to hide the default message    
    eventArgs.set_cancel(true);
}

function region_OnClientSelectedIndexChanged(sender, eventArgs) {
    searchText = sender._text;
}
function region_OnClientTextChange(sender, eventArgs) {
    searchText = sender._text;
}
function region_OnClientSelectedIndexChanging(sender, eventArgs) {
    searchText = sender._text;
}

function ClearSearchText(sel) {
    sel.value = '';
    sel.focus();
}
function onBlurSearchRegion() {
    this.value = searchText;
}