Previous screensaver setup isn't restored correctly on exit

When a QWS application exits it always sets a screensaver, even if none had been active before start. During runtime the screensaver had been disabled by QWSServer::setScreenSaver(NULL). This behaviour was observed with both QtE 4.5.3 and 4.6.0.
Expected behaviour: The QWS server should either restore the screensaver setup as it was before it has been started, or maintain the current setting made by the application.