Innovations of disruption

I like glazou’s latest idea. Considering he gave us HTML overlays, maybe we as the community owe him one.
I commented that it looked a lot like a DOM node filter. I wonder how hard it would be to write a JS to do what he’s suggesting, generically. I also would have to figure out how to import the script (maybe as a Mozilla component), particularly with respect to XML (which prefers <?xml-stylesheet ?>).
Daniel, I’m thinking about ways to implement this for you.