Visual GUI debugger

Hey,

Is there some visual debugger for m4? something like a video.
something you could play the file being expanded very slowly, maybe
with colored thingies.

I'm aware of GNU's m4 option --debug=V, I've been using it for now.
Very helpful!

In the past few days I've been advancing my m4 knowledge a lot as I
devise two solutions to generate code for things that lack
metaprogramming, such as Ragel. I'll share my code soon enough.

If no such debugger exists, I might develop one myself in the next two
years. I'll likely literally create a video parsing --debug=V output,
or I might create an actual GUI client. I'll ponder.

Best regards,
Bento Borges Schirmer