private async void ConvertToHtml()
        {
            VisualStateManager.GoToElementState(GridMain, "HtmlShown", false);

            DrawingMode mode = GetDrawingMode();

            HtmlConverter converter = new HtmlConverter(CreateOptions(), mode);

            try
            {
                Progress <double> progress = new Progress <double>(UpdateProgress);
                WvAscii.NavigateToString(await converter.ConvertAsync(_source, progress));
            }
            catch (Exception e)
            {
                MessageBox.Show(e.Message, "Operation failed!");
            }
        }