api.cs

public static class TextControlExtensions
{
    public static void LoadMarkdown(this TXTextControl.TextControl textControl,
                                    string markdown)
    {
        textControl.Load(ParseMarkdown(markdown), TXTextControl.StringStreamType.HTMLFormat);
    }

    private static string ParseMarkdown(string markdownInput)
    {
        var pipeline = new MarkdownPipelineBuilder().UseAdvancedExtensions().Build();
        return Markdown.ToHtml(markdownInput, pipeline);
    }
}