C#

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   <div id="replyuser" style=" position:absolute;"><asp:TextBox ID="txt1" CssClass="txtbox" TextMode="MultiLine" runat="server"></asp:TextBox><br /><asp:Button ID="btnreply" Text="send" runat="server" CssClass="btn" /></div>

$(document).ready(function() {
           $("#replyuser").hide();

           $("#reply").click(function() {

               $("#replyuser").toggle(function() {

             $("#reply").text("close");
               });

           });
       });

public static  void CampoTxt(Panel frmPadre)
{
TextBox txt = new TextBox();
txt.Name = "name";
txt.Visible = true;
frmPadre.Controls.Add(txt);
}            

private void pnlf_ControlAdded(object sender, ControlEventArgs e)
        {
            ...some code ....
        }

Assembly ctClientServerLib = Assembly.LoadFrom(string.Concat(bfcSetupFolder, "Interop.CtClientServerLib.dll"));


Type applicationClientClass = ctClientServerLib.GetType("CTCLIENTSERVERLib.CtApplicationClientClass");
Type ictSession = Type.GetTypeFromCLSID(new Guid("BCB06C70-AF26-11D3-8C89-00C04F517D7D"));
Type ictProtectedSession = ctClientServerLib.GetType("CTCLIENTSERVERLib.ICtProtectedSession");
Type ictSessionCtx = Type.GetTypeFromCLSID(new Guid("5F852A70-7E77-11D4-8CE1-00C04F517D7D"));

Type ictSessionClient = Type.GetTypeFromCLSID(new Guid("2C3444F9-ED6D-4700-B2EC-F665569FE830"));
Type ictProviderContainer = Type.GetTypeFromCLSID(new Guid("797BB105-AEDF-11D3-8C89-00C04F517D7D"));
Type ictProviderContainer = Type.GetTypeFromCLSID(new Guid("797BB105-AEDF-11D3-8C89-00C04F517D7D"));

object session;
object res;

res = applicationClientClass.InvokeMember("ConnectToServer", BindingFlags.InvokeMethod, System.Type.DefaultBinder, cacc, new object[] { "MyServer", "MyDataBase", new String[] { } });

session = applicationClientClass.InvokeMember("Logon", BindingFlags.InvokeMethod, System.Type.DefaultBinder, cacc, new object[] { "ADMIN", "" });

res = applicationClientClass.InvokeMember("Initialize", BindingFlags.InvokeMethod, System.Type.DefaultBinder, cacc, new object[] { session });

//I initialize my session and it works fine.

/*Now I need to cast my session (which is an interface called ICtSession)*/

/*ictSession and ictSession is the same interface. I just needed to get type by CLSID for Marshal.CreateWrapperOfType*/
Type ictSession2 = ctClientServerLib.GetType("CTCLIENTSERVERLib.ICtSession");

Type ictSessionCtx2 = ctClientServerLib.GetType("CTCLIENTSERVERLib.ICtSessionCtx");
Type ictSessionClient2 = ctClientServerLib.GetType("CTCLIENTSERVERLib.ICtSessionClient");
Type ictProviderContainer2 = ctClientServerLib.GetType("CTCLIENTSERVERLib.ICtProviderContainer");


var session2 = Marshal.CreateWrapperOfType(session, ictSession);
var sessionClient = Marshal.CreateWrapperOfType(session2, ictSessionClient);
var sessionCtx = Marshal.CreateWrapperOfType(sessionClient, ictSessionCtx);


res = ictSessionCtx2.InvokeMember("SetSessionCtx", BindingFlags.InvokeMethod, System.Type.DefaultBinder, sessionCtx, new object[] { });

var providerContainer = Marshal.CreateWrapperOfType(sessionClient, ictProviderContainer);

/*This method fail !!! I have Exception de HRESULT : 0x80020006 (DISP_E_UNKNOWNNAME)*/
object objectManagerClient = ictProviderContainer2.InvokeMember("get_Provider", BindingFlags.InvokeMethod, System.Type.DefaultBinder, sessionClient, new object[] { 1, -523387 });

/* So I suppose that the cast had failed because I'm sure that ictProviderContainer contains the method get_Provider(int, int) (I checked with ictProviderContainer2.GetMethods()) */.