By going via QWidget::close() we ensure that if there's a QWidgetWindow
backing the dialog (which is almost always the case), we will plumb down
to QWindow::close(), resulting in QEvent::Close events to the QWindow.
Since we don't want QDialog subclasses to receive a call to a closeEvent
override that they didn't receive before (and which they might interpret
as rejection or cancellation), install a temporary event filter that
eats the QCloseEvent resulting from the call to close().
Task-number: QTBUG-53286
Change-Id: Ie8f6f0cb3160acfd5865dc74f0a7b6d87f838724
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>