Sorry, I completely missed this post...
Only published properties have RTTI, but IpHtmlNodes only declare public properties. Please try the attached IpHtml unit in which I published most of the node properties - in my own experiments it seems to be working, although a lot of properties are marked as "unsupported" - maybe the selection of published properties is not yet correct.
The HTML nodes tree is a nice idea and very useful for debugging. Is it one of the Delphi examples, or is it your code? In the latter case, would you allow me to add it to the ported examples for Lazarus?