Unlike the typical client/server situation, my chat application is both a client and a server. It is a server because it runs an instance of qtcpserver and it is a client, because you can make connections using qtcpsocket.

To have multiple connections i assumed you need multithreading although I have no experience with multithreading+ I'm new to QT.

Here is how I'm implementing the ability to establish a connection and then pass off that connection to its own thread.

Qt Code: 
  1. // background info 
  2.    MSocket tcpSocket;
  3.  
  4.     connect(&tcpSocket, SIGNAL(connected()), 
  5. 	  this, SLOT(connectionEstablished()));
  6.  
  7.     tcpSocket.connectToHost(remoteIP, remotePort);
  8.  
  9. // end background. 
  10.  
  11. void MChat::connectionEstablished() {
  12.   chatOutput->append("<font color=green>Connection Established.</font>");
  13.   MSocketThread* mSockThread = new MSocketThread(tcpSocket.socketDescriptor());
  14.   connect(this, SIGNAL(sendText(QString&)), 
  15. 	  mSockThread, SIGNAL(sigSend(QString&)));
  16.   connect(mSockThread, SIGNAL(relayIncomingText(QString&)), 
  17. 	  this, SLOT(outputText(QString&)));
  18.   connect(mSockThread, SIGNAL(socketError()),
  19. 	  this, SLOT(error()));
  20.   connect(mSockThread, SIGNAL(finished()), 
  21. 	  mSockThread, SLOT(deleteLater()));
  22.   mSockThread->start();
  23.  
  24. }
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Here's how I'm implementing the MSocketThread

Qt Code: 
  1. void MSocketThread::run() {
  2.   MSocket mSocket;
  3.   if ( !mSocket.setSocketDescriptor(socketDescriptor) ) {
  4.     emit error(mSocket.error());
  5.     return; 
  6.   }
  7.   connect(&mSocket, SIGNAL(inboundText(QString&)), 
  8. 	  this, SIGNAL(relayIncomingText(QString&)));
  9.   connect(this, SIGNAL(sigSend(QString&)), 
  10. 	  &mSocket, SLOT(send(QString&)));
  11.   /* 
  12.      connect(mSocket, SIGNAL(error(QAbstractSocket::SocketError)),
  13. 	  this, SIGNAL(socketError()));
  14.   */
  15.   mSocket.waitForDisconnected();
  16.  
  17.  
  18. }
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Finally, here is the problem I'm encountering. When I try to send some chat, the console window displays this message:
QObject::connect: Cannot queue arguments of type 'QString&'
(Make sure 'QString&' is registed using qRegisterMetaType().)
And no chat gets displayed on the remote chat app. output.

Any tips, solutions, etc. are welcome as I am very new.