May 25, 2015: This project is not dead (yet). We're on out third hack doing this having taken several wrong turns as far as which tags actually need to be written out as code and which can be included as comments (like custom tags).
But as an addendum, I'd like to add, that if this works (at all) it will be useful for seeing how to write a gtk application by hand by outputting working code for whichever tags it ends up handling correctly. And for those it doesn't handle correctly...