Josh
XML doesn't really lend well to true WYSIWYG editors. Since the file is parsed to then configure some aspect of something. Since this is LotRO GUI I assume you want one to edit or create a custom UI for LotRO.
There is a tool on this site for doing that sort of thing that will once you go through the options, I think, create the correct XML and the like for a custom UI.
Is that what you are looking for?
LOTRO Skin Editor:
http://www.lotrointerface.com/downlo...kinEditor.html