C#如何写触发toolbar里的toolbardropdownlist的selectchanged事件

see that example：<%@ Register TagPrefix="iewc" Namespace="Microsoft.Web.UI.WebControls" Assembly="Microsoft.Web.UI.WebControls, Version=1.0.2.226, Culture=neutral, PublicKeyToken=31bf3856ad364e35" %>
<HTML>
<HEAD>
<script language=C# runat=server>
public void myFunc(object sender, System.EventArgs e)
{
ToolbarDropDownList t=(ToolbarDropDownList)Toolbar1.Items[0];
Response.Write(t.SelectedItem.Text);
}
</script>
</HEAD>
<body MS_POSITIONING="GridLayout">
<form id="WebForm1" method="post" runat="server">
<iewc:Toolbar id="Toolbar1" runat="server" AutoPostBack="True">
<iewc:ToolbarDropDownList AutoPostBack="True" onSelectedIndexChanged="myFunc">
<asp:ListItem Value="aaa" Selected="True">aaa</asp:ListItem>
<asp:ListItem Value="bbb">bbb</asp:ListItem>
</iewc:ToolbarDropDownList>
</iewc:Toolbar>
</form>
</body>
</HTML>