telerik:RadComboBox runat="server" Skin="Web20" ID="RadComboBox1" Height="190px" Width="420px"

MarkFirstMatch="true"

EnableLoadOnDemand="true"

HighlightTemplatedItems="true"

OnClientItemsRequested="UpdateItemCountField"

OnDataBound="RadComboBox1_DataBound"

OnItemsRequested="RadComboBox1_ItemsRequested">

<ItemTemplate>

<asp:CheckBox runat="server" ID="chk1" onclick="onCheckBoxClick(this);" />

<asp:Label runat="server" ID="Label1" AssociatedControlID="chk1"><%# Eval("CodeDesc")%>

</asp:Label>

</ItemTemplate>

<FooterTemplate>

<asp:Literal runat="server" ID="RadComboItemsCount" /> items

</FooterTemplate>

</telerik:RadComboBox>

MultiSelectCombo.ascx.cs
=====================

public

partial class MultiSelectCombo : BaseControl

{

protected void Page_Load(object sender, EventArgs e)

{

if (!Page.ClientScript.IsClientScriptBlockRegistered("MultiSelectComboIDBlock"))

{

Page.ClientScript.RegisterClientScriptBlock(

this.Page.GetType(), "MultiSelectComboIDBlock", "var MultiSelectComboID = '" + RadComboBox1.ClientID + "';", true);

}

}

protected void RadComboBox1_DataBound(object sender, EventArgs e)

{

//set the initial footer label

((

Literal)RadComboBox1.Footer.FindControl("RadComboItemsCount")).Text = Convert.ToString(RadComboBox1.Items.Count);

}

protected void RadComboBox1_ItemsRequested(object sender, RadComboBoxItemsRequestedEventArgs e)

{

RadComboBox1.DataSource =

Shared.tdsStaticReference.User;

RadComboBox1.DataBind();

}

}

MultiSelectCombo.js
================

function

UpdateItemCountField(sender, args) {

//set the footer text

sender.get_dropDownElement().lastChild.innerHTML =

"A total of " + sender.get_items().get_count() + " items";

}

var cancelDropDownClosing = false;

function onDropDownClosing() {

cancelDropDownClosing =

false;

}

function onCheckBoxClick(chk) {

var combo = $find(MultiSelectComboID);

alert(combo);

//prevent second combo from closing

cancelDropDownClosing =

true;

//holds the text of all checked items

var text = "";

//holds the values of all checked items

var values = "";

//get the collection of all items

var items = combo.get_items();

//enumerate all items

for (var i = 0; i < items.get_count(); i++) {

var item = items.getItem(i);

//get the checkbox element of the current item

var chk1 = $get(combo.get_id() + "_i" + i + "_chk1");

if (chk1.checked) {

text += item.get_text() +

";";

values += item.get_value() +

",";

}

}

//remove the last comma from the string

text = removeLastSemicolon(text);

values = removeLastComma(values);

if (text.length > 0) {

//set the text of the combobox

combo.set_text(text);

combo.set_value(values);

}

else {

//all checkboxes are unchecked

//so reset the controls

combo.set_text(

"");

combo.set_value(

"");

}

}

//this method removes the ending comma from a string

function removeLastComma(str) {

return str.replace(/,$/, "");

}

function removeLastSemicolon(str) {

return str.replace(/;$/, "");

}

function OnClientDropDownClosingHandler(sender, e) {

//do not close the second combo if

//a checkbox from the first is clicked

e.set_cancel(cancelDropDownClosing);

}