Disable + checked QRadioButton in a buttongroup

int main(int argc, char *argv[]) {
 QApplication app(argc, argv);

 QWidget *widget = new QWidget;
 QVBoxLayout layout;
 widget->setLayout(&layout);

 QRadioButton* b1 = new QRadioButton("RADIOBUTTON1", widget);
 QRadioButton* interested = new QRadioButton("RADIOBUTTON2", widget);
 QRadioButton* b3 = new QRadioButton("RADIOBUTTON3", widget);

 interested->setDisabled(true);
 interested->setChecked(true);

 layout.addWidget(b1);
 layout.addWidget(interested);
 layout.addWidget(b3);
 widget->show();

 return app.exec();
}