Try/Catch in reimplemented QApp::notify does not working on Mac OsX

class App: public QApplication{
public:
...
    bool notify(QObject *o, QEvent *e){
        try
        {
                return QApplication::notify(o, e);
        }
        catch(...){
            QMessageBox::information(0,tr("Error"),tr("Press OK to continue."));
        }
    }
}

int main(int argc, char *argv[])
{
    App a(argc, argv);
    try{
       MainWindow w;
       w.resize(900,700);
       w.show();

      return a.exec();
    }catch(..){
        QMessageBox::information(0,"Critical error","Press OK to close program");
     }
}