QChart *chart = new QChart(); // has no parent!
chart->legend()->hide();

QLineSeries *series = new QLineSeries(chart);
chart->addSeries(series);
chart->createDefaultAxes();
chart->layout()->setContentsMargins(0, 0, 0, 0);

QChartView *chartView = new QChartView(chart);

dialog = new QDialog(this);
QVBoxLayout *layout = new QVBoxLayout;
layout->addWidget(chartView);
dialog->setLayout(layout);

connect(dialog, &QObject::destroyed, [this, index](){
plots_cn0.erase(index.row());
});

connect(&updateTimer, &QTimer::timeout, [this, series, index](){
QVector<QPointF> points;
QList<QVariant> var = index.data(Qt::DisplayRole).toList();
for(int i = 0; i < var.size(); i++)
{
    points << var.at(i).toPointF();
}

series->replace(points);
});

plots_cn0[index.row()] = qMakePair(chart, dialog);