Gist Addin OnExecute() code that fires off the Addin's UI.

file.cs

public override void OnExecute(object sender)
{
    var editor = GetMarkdownEditor();
    if (editor == null)
        return;
            
    var gist = new GistItem()
    {
        code = editor.AceEditor.getselection(false),
        language = "cs"
    };

    var form = new PasteCodeAsGitWindow(this);            
    form.Owner = Model.Window;
    form.Gist = gist;
    form.ShowDialog();

    if (form.Cancelled)
        return;

    if (!string.IsNullOrEmpty(gist.embedUrl))
        editor.SetSelectionAndFocus($"<script src=\"{gist.embedUrl}\"></script>\r\n");

    Model.Window.ShowStatus("Gist embedded", 5000);
    Model.Window.SetStatusIcon(FontAwesomeIcon.GithubAlt, Colors.Green);
}