Modal Popup Always Visible

DialogRestoreEventArgs.cs
----------------------------

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data;
    public class DialogRestoreEventArgs
    {
        Dictionary<string, string> _paramValues = null;
        public DialogRestoreEventArgs()
        {
            _paramValues = new Dictionary<string, string>();
        }
        public Dictionary<string, string> ArgumentValues
        {
            get
            {
                return _paramValues;
            }
            set
            {
                _paramValues = value;
            }
        }
        public void AddParam(string key, string value)
        {
            if (_paramValues == null)
                _paramValues = new Dictionary<string, string>();
            if (_paramValues.ContainsKey(key))
                throw new DuplicateNameException(string.Format("Parameter {0} already exist in argument collection", key));
            _paramValues.Add(key, value);
        }
        public string GetParam(string key)
        {
            if (_paramValues == null)
                return string.Empty;
            if (!_paramValues.ContainsKey(key))
                throw new ArgumentException(string.Format("Parameter key {0} not found in collection", key));
            return _paramValues[key];
        }
    }

Email.ascx
--------------
<%@ Control Language="C#" AutoEventWireup="true" CodeFile="Email.ascx.cs" Inherits="MyCollections.UserControls_Email" %>
<asp:Button ID="Button1" runat="server" Text="Button" OnClick="Button1_Click" />
Email.ascx.cs
-----------------
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace MyCollections
{
    public partial class UserControls_Email : System.Web.UI.UserControl
    {
        public delegate void DialogRestoreEventHandler(object senders, DialogRestoreEventArgs e);
        public event DialogRestoreEventHandler RestoreModalDialog;
        
        protected void Button1_Click(object sender, EventArgs e)
        {
            if (RestoreModalDialog != null)
            {
                DialogRestoreEventArgs evnts = new DialogRestoreEventArgs();
                RestoreModalDialog(sender, evnts);
            }
        }
    }
}

Default.aspx
--------------
<%@ Page Title="Home Page" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true"
    CodeFile="Default.aspx.cs" Inherits="_Default" %>
<%@ Register Src="~/UserControls/Email.ascx" TagName="CustomerEmail" TagPrefix="CustEmail" %>
<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="asp" %>
<asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent">
</asp:Content>
<asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent">
    <asp:ScriptManager ID="ScriptManager1" runat="server">
    </asp:ScriptManager>
 
    
    <asp:Button ID="btn1" runat="server" Text="Submit" />
    <div id="myMailDiv" style="width: 50%; height: 50%;">
    <asp:Button runat="server" ID="btnSendMail" Style="display: none" />
    <asp:ModalPopupExtender ID="ModelpopEmail" runat="server" TargetControlID="btn1"
        PopupControlID="panelSendEmail" BackgroundCssClass="modalBackground">
    </asp:ModalPopupExtender>
    <asp:Panel ID="panelSendEmail" runat="server" BackColor="white" BorderColor="Black">
        <div id="emailDiv" style="border: 1px solid #666666; padding: 5px;">
            <div id="customerinfogrid" style="width: 97%;">
                <div id="gridimg">
                  <%--  <img src="Images/emailthisproperty.png">--%>
                </div>
                <div id="gridtxt">
                    Customer Email
                </div>
            </div>
           <%-- <asp:Button ID="Button1" runat="server" Text="Cancel" OnClick="btncancel_Click" />--%>
            <div>
                <asp:PlaceHolder ID="PlaceHolder1" runat="server"></asp:PlaceHolder>
                <CustEmail:CustomerEmail ID="CustomerEmail1" runat="server" />
                
          
            </div>
           <asp:Button ID="btncancel" runat="server" Text="Cancel" OnClick="btncancel_Click" />
            <asp:Button ID="btnOpen" runat="server" Text="Open" OnClick="btnOpen_Click" />
        </div>
          
    </asp:Panel>
</div>
</asp:Content>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using MyCollections;
public partial class _Default : System.Web.UI.Page
{
   
    protected override void OnInit(EventArgs e)
    {
        base.OnInit(e);
        
        CustomerEmail1.RestoreModalDialog += new UserControls_Email.DialogRestoreEventHandler(CustomerEmail1_RestoreModalDialog);
    }
    void CustomerEmail1_RestoreModalDialog(object senders, DialogRestoreEventArgs e)
    {
        ModelpopEmail.Show();
    }
    
    protected void Button_Click(object sender, EventArgs e)
    {
        ModelpopEmail.Show();
    }
    protected  void Page_Load(object sender,EventArgs e)
    {
      //  base.OnInit(e);
      //  btn1.Click += new EventHandler(btnShowText_Click);
    }
    
    void btnShowText_Click(object senders, EventArgs e)
    {
      //  ModelpopEmail.Show();
    }
    protected void btncancel_Click(object senders, EventArgs e)
    {
        ModelpopEmail.Hide();
    }
    //btnOpen_Click
    protected void btnOpen_Click(object senders, EventArgs e)
    {
        ModelpopEmail.Show();
    }
    static void Button1_Click(object o, EventArgs e)
    {
            //Console.WriteLine("Event being called.");
            //Console.ReadLine();
    }
    protected static void OnMyTestEvent(object sender, EventArgs e)
    {
        
    }
}

Calling Server Function using JavaScript

Default.aspx
----------------
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default5.aspx.cs" Inherits="Default5" %>
<!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 runat="server">
    <title>Untitled Page</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
    <asp:Label ID="lblmsg" runat="server"></asp:Label>
    </div>
    </form>
</body>
</html>
Default.aspx.cs
-------------------
using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Text;
public partial class Default5 : System.Web.UI.Page
{
    public string click()
    {
        lblmsg.Text = "This is function";
        string msg = lblmsg.Text;
       
        ClientScript.RegisterClientScriptBlock(GetType(), "", "<script>alert('" + msg.ToString() + "');</script>");
       
        return msg;
    }
    protected void Page_Load(object sender, EventArgs e)
    {
        StringBuilder sb = new StringBuilder();
        sb.Append("bool i = document.getElementById('<%=btnsubmit.ClientID%').value");
        sb.Append("if(i == true)");
        sb.Append("{");
        sb.Append("'" + click() + "'");
      
        sb.Append("}");
        sb.ToString();
        ClientScript.RegisterClientScriptBlock(GetType(), "clientscript", "<script>alert('" + click() + "');</script>");
    }
}

Find Which Button is Clicked and load User Control

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default4.aspx.cs" Inherits="Default4" %>
<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit"  TagPrefix="cc1" %>
<%@ Register Src="~/Controls/UC1.ascx" TagName="UC1" TagPrefix="UC1" %>
<%@ Register Src="~/Controls/UC2.ascx" TagName="UC2" TagPrefix="UC2" %>
<%@ Register Src="~/Controls/UC3.ascx" TagName="UC3" TagPrefix="UC3" %>
<!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 runat="server">
    <title>Untitled Page</title>
    <script type="text/javascript">
        function doTest() {
            var button = document.getElementById("btnHome");
            button.value = "Home";
            alert("button contents = " +  button.value);
            var hdn = document.getElementById("hdnTextboxName");
            hdn.value = button.value;
            return true;
        }
        function doTest2() {
            var button = document.getElementById("btnContact");
            button.value = "Contact";
            alert("button contents = " + button.value);
            var hdn = document.getElementById("hdnTextboxName");
            hdn.value = button.value;
            return true;
        }
        function doTest3() {
            var button = document.getElementById("btnPhone");
            button.value = "Phone";
            alert("button contents = " + button.value);
            var hdn = document.getElementById("hdnTextboxName");
            hdn.value = button.value;
            return true;
        }
    </script>
    
    
     <style type="text/css">
    .Button
       {
        background-color: #316ac4;
        width:75px;  
        height:25px;          
        padding: 0;
        color:Black;
        cursor:pointer;
        color:White;
        font-weight:bold; 
        margin-top:0px;
         
         -moz-border-radius: 15px;
         -webkit-border-radius: 15px;
         -khtml-border-radius: 15px;
          behavior: url(/border-radius.htc);  border-radius: 15px;
          
         }
    </style>
    
</head>
<body>
    <form id="form1" runat="server">
    <div>
         <asp:ScriptManager ID="sc1" runat="server" ></asp:ScriptManager>
    
      <asp:UpdatePanel ID="UpdatePanel4" runat="server">
       <ContentTemplate>
       
    <asp:Panel ID="pnlTest" runat="server"  DefaultButton="btnHome">
       <table border="1"  width="700px" bgcolor="#316ac4" style="margin-left:100px;">
       <tr>
       <td>
       Textbox:
            <asp:TextBox ID="txtTest" runat="server" />
            <asp:TextBox ID="txtContact" runat="server"></asp:TextBox>
           <asp:TextBox ID="txtPhone" runat="server"></asp:TextBox>
           <asp:HiddenField ID="hdnTextboxName" runat="server" />
     
       </td>
       </tr>
       </table>
     </asp:Panel>
             
        <table border="1"  width="700px" bgcolor="#316ac4" style="margin-left:100px;">
        <tr>
        <td>
        <asp:Button ID="btnHome" runat="server" Text="Home" OnClientClick="doTest()"  CssClass="Button"/>                        
            <asp:Button ID="btnContact" runat="server" Text="Contact" OnClientClick="doTest2()"  CssClass="Button"/>                        
            <asp:Button ID="btnPhone" runat="server" Text="Phone" OnClientClick="doTest3()"  CssClass="Button"/>                        
 
        </td>
        </tr>
        </table>   
           
      </ContentTemplate>
      </asp:UpdatePanel> 
        
     
    
   <table border="1"  width="700px" height="500px" style="margin-left:100px;">
       <tr>
       <td>
     <asp:Panel ID="Panelmain" runat="server">
       <asp:UpdatePanel ID="UpdatMain" runat="server">
       <ContentTemplate> 
       <asp:Panel ID="Panel1" runat="server">
        <asp:UpdatePanel ID="UpdatePanel1" runat="server">
          <ContentTemplate>
              <asp:Button ID="btn1" runat="server"   Visible="false"/>
          </ContentTemplate>
          
           <Triggers>
          <asp:AsyncPostBackTrigger ControlID="btn1" />
          </Triggers>
          </asp:UpdatePanel>
          </asp:Panel>
          
       
       <asp:Panel ID="Panel2" runat="server">
        <asp:UpdatePanel ID="UpdatePanel2" runat="server">
          <ContentTemplate>
              <asp:Button ID="btn2" runat="server"   Visible="false"/>
          </ContentTemplate>
          
           <Triggers>
          <asp:AsyncPostBackTrigger ControlID="btn2" />
          </Triggers>
          </asp:UpdatePanel>
          </asp:Panel>
      
       
       
          <asp:Panel ID="Panel3" runat="server">
          <asp:UpdatePanel ID="UpdatePanel3" runat="server">
          <ContentTemplate>
          <asp:Button ID="btn3" runat="server"   Visible="false"/>
          </ContentTemplate>
          
          <Triggers>
          <asp:AsyncPostBackTrigger ControlID="btn3" />
          </Triggers>
          </asp:UpdatePanel>
          </asp:Panel>
       
       </ContentTemplate>
       </asp:UpdatePanel>
       
     </asp:Panel>
       </td>
       </tr>
       </table>   
    </div>
    </form>
</body>
</html>

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
public partial class Default4 : System.Web.UI.Page
{
    ASP.controls_uc1_ascx uc1 = new ASP.controls_uc1_ascx();
    ASP.controls_uc2_ascx uc2 = new ASP.controls_uc2_ascx();
    ASP.controls_uc3_ascx uc3 = new ASP.controls_uc3_ascx();
   
    protected void Page_Load(object sender, EventArgs e)
    {
        if (hdnTextboxName.Value == "Home")
        {
            txtTest.Text = hdnTextboxName.Value;
            uc1.LoadControl("~/Controls/UC1.ascx");
            Panel1.Controls.Add(uc1);
         //   ClientScript.RegisterClientScriptBlock(GetType(), "clientscript", "<script> alert('This is Tab1'); </script>", false);
        }
        if (hdnTextboxName.Value == "Contact")
        {
            txtContact.Text = hdnTextboxName.Value;
            uc2.LoadControl("~/Controls/UC2.ascx");
            Panel2.Controls.Add(uc2);
          //  ClientScript.RegisterClientScriptBlock(GetType(), "clientscript", "<script> alert('This is Tab2'); </script>", false);
            
        }
        if (hdnTextboxName.Value == "Phone")
        {
        txtPhone.Text = hdnTextboxName.Value;
        uc3.LoadControl("~/Controls/UC3.ascx");
        Panel3.Controls.Add(uc3);
       // ClientScript.RegisterClientScriptBlock(GetType(), "clientscript", "<script> alert('This is Tab3'); </script>", false);
           
        }
    }
}

Output: