Building XML editor in .NET 2.0
Thanks to Hannes Preishuber feedback,
I found how to write it with WebBrowser control (C# version)
object obj = webBrowser1.ActiveXInstance;
HtmlDocument hd = webBrowser1.Document;
IHTMLDocument2 axObj = hd.DomDocument as IHTMLDocument2;
axObj.designMode = "On";