problem retrieving data processed by class library

Question

Pls help! how am i going to update a form's listbox with data handled and stored by a class library ( the messages are  from a connected socket)?
I want this listbox to diplay chat messages.


class X (class library code)

properties: ipadd,port,isconnected...etc
methods:
    Connect()  and  ConnectCallback //will establish connection to the socket using BeginConnect and EndConnect
    WaitForData and OnDataReceived(Callback) //will received the messages using BeginReceive and EndReceive
 

        public void WaitForData()
        {
            recieveCallback = new AsyncCallback(onDataReceived);
            StateObject socket = new StateObject();
            socket.workSocket = mainClientSocket;
            result = mainClientSocket.BeginReceive(socket.buffer, 0, socket.buffer.Length, SocketFlags.None,   recieveCallback, socket);
        }

        private void onDataReceived(IAsyncResult result)
        {
            StateObject socket = (StateObject)result.AsyncState;
            if (mainClientSocket.Connected)
            {

                bytesRcvd = socket.workSocket.EndReceive(result);
                ReadXML(bytesReceived, socket);  //method that will parse the message
                receiveDone.Set();
                WaitForData();
            }
            else
            {
                socket.workSocket.Close();
            }
        }


      
        private void ReadXML(int bytes, StateObject socket)
        {
          ...
          ...
          ...
          Once data is parsed , it will be stored in SenderMessageList   ///(List<string>)
            SenderMessageQueue(Sender + ": " + Message);
        }
        private void SenderMessageQueue(String message, String socketID)
        {
            SenderMessageList.Add(message);
        }

        public String getSenderMessage                                 //// I will call this property in a form to display                                                                //// the  stored message
        {
            get
            {
                return SenderMessageList[SenderMessageList.Count - 1];  
            }
        }

Form  // will use the library


namespace WindowsFormsApplication4
{
            using X;
           ..
           ..
            x= new X.ClientSocket();
            IntPtr handle = this.Handle;
            x.IPadd = "127.0.0.1";
            x.Port = 8222;
            x.Connect();
            
            ThreadStart threadStarter = new ThreadStart(ReceiveMessages);
            myThread = new Thread(threadStarter);
            myThread.IsBackground = true;
            myThread.Start();
        }

        private void ReceiveMessages()
        {
        
            while (x.bytesReceived != 0)
            {
                 listBox1.Invoke(new UpdateTextCallback(this.Update_listBox1), new object[] { a });
                
            }
            listBox1.Invoke(new UpdateTextCallback(this.Update_listBox1), new object[] { x.getSenderMessage });
         }

        private void Update_listBox1(String text)
        {
            listBox1.Items.Add(text);
            
        }
        private void ButtonSend_click{
            }

When i move the listbox.invoke in ButtonSend, i can get the stored message..But what i want to do is automate the receiving of data..Sending has no problem cause it's working...I am by the way creating a chat program..i want to see all the messages coming in...Thanks.