QwtPlotMarker *mX = new QwtPlotMarker();
mX->setLabel(QString::fromLatin1("base marker"));
mX->setLabelAlignment(Qt::AlignLeft | Qt::AlignBottom);
mX->setLabelOrientation(Qt::Vertical);
mX->setLineStyle(QwtPlotMarker::VLine);
mX->setLinePen(QPen(Qt::red, 3, Qt::SolidLine));
mX->setXValue(50000);
mX->attach(this);