<%@ Page Language="C#" %>
<%@ OutputCache Duration="60" VaryByParam="Color" %>
<script language="C#" runat="server">
void Btn_Click(Object sender, EventArgs e) {
Msg.Text = "You selected : " + Color.SelectedItem.Value;
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<body>
<% Response.Write("Page generated at : " + DateTime.Now); %> <br/>
<center>
<form id="Form1" action="Default.aspx" method="post" runat="server">
Color : <asp:dropdownlist id="Color" runat="server">
<asp:listitem>white</asp:listitem>
<asp:listitem>black</asp:listitem>
</asp:dropdownlist>
<br/>
<asp:button id="Button1" text="Submit" OnClick="Btn_Click"
runat="server"/>
<br/>
<asp:label id="Msg" runat="server"/>
</form>
</center>
</body>
</html>