Painting artefacts when using QPen with style other than SolidLine in QGraphicsView

#include <QtGui>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
	QMainWindow w;


	QGraphicsScene* s = new QGraphicsScene(&w);
	QGraphicsView* v = new QGraphicsView(s);
	s->setSceneRect(-1000,-1000,3000,3000);

	w.setCentralWidget(v);

	QRectF circleRect(0,0,600,600);
	QGraphicsEllipseItem* el = new QGraphicsEllipseItem(circleRect);
	el->setPen(QPen(Qt::red, 4, Qt::DashLine));
	s->addItem(el);

    w.show();
    return a.exec();
}