delete ui;

    ui = NULL; // we check if ui is deleted in messageHandler

}

void MainWindow::closeEvent(QCloseEvent * event)

{

    // save snapshots

    if (!snapshotMan.isAllSaved())

    {

        auto clickedButton = QMessageBox::warning(

            this, "Closing SerialPlot",

            "There are un-saved snapshots. If you close you will loose the data.",

        if (clickedButton == QMessageBox::Cancel)

        {

            event->ignore();

            return;

        }

    }

    // save settings

    QSettings settings("serialplot", "serialplot");

    saveAllSettings(&settings);

    settings.sync();