public MainWindow()
        {
            InitializeComponent();
            try
            {
                PdfPreview.OpenFile(previewPath);

                System.Windows.Threading.DispatcherTimer dispatcherTimer = new System.Windows.Threading.DispatcherTimer();
                dispatcherTimer.Tick    += dispatcherTimer_Tick;
                TextEntry.TextChanged   += dispatcherTimer_Tick;
                dispatcherTimer.Interval = new TimeSpan(0, 0, 120);
                dispatcherTimer.Start();
            }
            catch
            {
            }
        }
 private void dispatcherTimer_Tick(object sender, EventArgs e)
 {
     // formatting to PDF and save result to file
     MarkdownPdf.Transform(TextEntry.Text, previewPath);
     PdfPreview.OpenFile(previewPath);
 }