title: What is QTcpSocket's behaviour when the network is overloaded?
body: <p>I have a QTcpSocket in a seperate thread sending a lot of data. Several of these applications are spread out over the network.</p>
  
  <p>How can I detect whether my network is overloaded and my socket is not able to send anything anymore? Will QTcpSocket buffer all data, how can I see the size of my buffered data that is queueing to be sent? Will this equal bytesToWrite()? Is there a maximum bytesToWrite()?</p>
  
  <p>If QTcpSocket starts discarding data, which data will it be: oldest in buffer queue, newest in buffer queue,...?</p>