When QObject::deleteLater() is called before QApplication::exec(), the documentation says that the events are processed as soon as the event loop is entered. I can observe this behaviour.

However, when I call QApplication::processEvents() before QApplication::exec(), possibly also via a modal QDialog::exec(), the DeferredDelete is only carried out after QApplication::quit()!

I will attach example code. Change the

#define PROCESS_EVENTS 1

to see the differing behaviour.

I would have expected the DeferredDelete to actually be processed either in the processEvents() call or at latest on QApplication::exec().