[4.4.0] QToolButton::setPopupMode() - impossible to disable pop-up menu if it was set before

#include <QtGui>

int main( int argc, char * argv[] )
{
    QApplication app( argc, argv );
    QToolButton * toolButton = new QToolButton;
    toolButton->setPopupMode( QToolButton::MenuButtonPopup );

    // NONE OF THESE MAKES THE ARROW HIDDEN FROM NOW ON
    toolButton->setMenu( 0 );
    toolButton->setArrowType( Qt::NoArrow );

    toolButton->show();
    return app.exec();
}