QtIFW

Fix null pointer exception in silent mode

Running in silent mode (using gui.setSilent(true) in a controller script)
QApplication::activeWindow() returns a null pointer as no application window
has the focus.

Change-Id: I440746b540110ebf336b6078b87b250660ee95be
Task-number: QTIFW-764
Reviewed-by: Katja Marttila <katja.marttila@theqtcompany.com>
Reviewed-by: Kai Koehne <kai.koehne@theqtcompany.com>