<%@ Page EnableViewState="True" Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs"
    Inherits="_Default" %>

<%@ Register Assembly="Telerik.Web.UI" Namespace="Telerik.Web.UI" TagPrefix="telerik" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <title>Untitled Page</title>
</head>
<body style="margin: 0px;">
    <form id="form1" runat="server">
    <asp:ScriptManager ID="ScriptManager1" runat="server">
    </asp:ScriptManager>

    <script type="text/javascript">
        function button_clicked() {

            var RadTextBox = $find("<%= txt.ClientID %>");

            if (RadTextBox == null) {
                alert("textbox is null")
            }
        }
    </script>

    <table cellpadding="0" cellspacing="0">
        <tr>
            <td width="80%">
                <%--                            <asp:textbox runat="server" TextMode="MultiLine" id="txt" style="WIDTH: 690px; HEIGHT: 260px" rows="16" Columns="79" ></asp:textbox>&nbsp;   
--%>
                <telerik:RadTextBox ID="txt" Width="690" Height="260" Rows="16" Columns="79" runat="server"
                    TextMode="MultiLine" SelectionOnFocus="CaretToEnd">
                </telerik:RadTextBox><br />
                <asp:TextBox ID="txtMsg" Width="400" runat="server"></asp:TextBox>&nbsp;&nbsp;
                <input id="btn" onclick="button_clicked()" type="button" value="SEND" class="btn" />
            </td>
        </tr>
    </table>
    </div>
    </form>
</body>
</html>
