If inherit QApplication, the MessageDialog accepted signal is emitted twice.

There is difference between WidgetMessageDialog and DefaultMessageDialog.

If inherit QApplication, it will use WidgetMessageDialog as MessageDialog QML type.

If not inherit QApplication and use QGuiApplication instead of it, it will use DefaultMessageDialog as MessageDialog QML type.

The accepted() signal will be emitted twice with WidgetMessageDialog  but once with DefaultMessageDialog .

I think it is a bug with WidgetMessageDialog.