After reading the existing documentation, samples and the articles in this forum, I am still not sure what is the HTMLUIControl object. From it''s constructors, one would conclude that it should be possible to render any HTML page - including those to be served from any Web server, but I had no luck getting this done. I believe that the strange name you assigned to this control indicates something :-)
Is this control really only rendering HTML documents stored on the local file system? If not why is your sample limited to this case?