this is an AjaxEvent. look at the example below
<%@ Page Language="C#" %>
<%@ Register Assembly="Coolite.Ext.Web" Namespace="Coolite.Ext.Web" TagPrefix="ext" %>
<!DOCTYPE html PUBLIC "-W3CDTD XHTML 1.0 TransitionalEN" "http:www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http:www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title></title>
<script runat="server">
protected void Page_Load(object sender, EventArgs e)
{
if (!Coolite.Ext.Web.Ext.IsAjaxRequest)
{
this.cbTemplate.Items.Clear();
this.cbTemplate.Items.Add(new Coolite.Ext.Web.ListItem("item 1", "1"));
this.cbTemplate.Items.Add(new Coolite.Ext.Web.ListItem("item 2", "2"));
this.cbTemplate.Items.Add(new Coolite.Ext.Web.ListItem("item 3", "3"));
this.cbTemplate.SetValue("1");
}
}
protected void PreviewTemplate(object sender, Coolite.Ext.Web.AjaxEventArgs e)
{
Ext.MessageBox.Alert("combobox items", this.cbTemplate.Items.Count.ToString()).Show();
}
</script>
</head>
<body>
<form id="form1" runat="server">
<ext:ScriptManager ID="ScriptManager1" runat="server">
</ext:ScriptManager>
<ext:ComboBox ID="cbTemplate" runat="server" Editable="false" Width="200" ForceSelection="true" Selectonfocus="true">
<AjaxEvents>
<Select OnEvent="PreviewTemplate">
</Select>
</AjaxEvents>
</ext:ComboBox>
</form>
</body>
</html>
after selecting a comboBox option, the alert displays "0".