The documentation claims that QGuiApplication forwards the top-level
windows. However this appears to be a search & replace mistake from the
QApplication <> QGuiApplication separation times. Only QApplication
forwards the event to top-level widgets and changeEvent() is a virtual
method of QWidget. Nothing is implemented for plain QGuiApplication and
QWindow.
Change-Id: I71b05ecebc90f7c28e150590764438ebaa90e88f
Reviewed-by: Michael Brasser <michael.brasser@live.com>