Thanks for that reply. I guessed as much that QApplication being a only-one-instance-at-a-time class would be the reason. But really, though I can conceptually understand your idea of a setApplicationDefaults() function which sets defaults for an application which is going to be started, who is going to write such a function if he/she is not going to create a QApplication object later?

There is only the small convenience of not having to use qApp or "this" whenever you have to set or read the properties of a QApplication. But then, we have no choice about using "this" or QWidget * or whatever whenever we have to set or read the properties of another QObject. So it might well have been the same for QApplication. When we write so many "this"-es for those objects, what's with a few for a QApplication object?

Anyway, your explanation is valid and I accept it. If anyone else has any other interesting perspectives I (and I presume you too) would be glad to hear it of course.