network connectivity with proxy


in Knights and in LabPlot I realized recently, while being in a corporate
network behind a proxy, that the connection to public internet servers is not
possible. E.g. in Khights the connection to the FICS-server is done like

QTcpSocket* socket = new QTcpSocket(this);
socket->connectToHost(address, port);

How to properly handle the proxy settings? Reading system settings (from the
environment?) and calling QTcpSocket::setProxy() or
QNetworkProxy::setApplicationProxy() somewhere in main.cpp doesn't sound to
me like the "standard way to do this".

In KDE's system settings there're already settings for the proxy. How to use
them and how to deal with this on windows and mac os x where this is not
available? Should the applications have this configuration in their settings?