I believe they did release the source code, not far from here: http://vpri.org/fonc_wiki/index.php?title=Installation_Guide (may be outdated, you may want to ask the FONC mailing list, may not work on your machine… it's a proof of concept anyway, not a hardened engineering artefact).
Their writing is here: http://vpri.org/html/writings.php
Their various reports are there (most recent first):
Granted, current GUI toolkits are huge. On the other hand, I have worked with Qt, and this convinced me most of the complexity there was a blend of avoidable bloat and a long tail of features few people ever use (a bit like offices suites).
I'm pretty sure properly written GUI toolkits can be much smaller. As in, satisfying 90% of our needs in a couple thousand lines of code. (The remaining 10% might require heaps and heaps of code, but I'm sure it doesn't have to affect the core.)
It's only an intuition at this point (I have yet to implement my own GUI toolkit). But I have reasons to believe this intuition is right: http://www.vpri.org/pdf/tr2012001_steps.pdf
> a fully-featured and usable (comparatively to today's personal computers) formally-specified... and proven computing system that goes from high-level language to operating system and application ecosystem to whatever machinery is used at the bottom.
The STEPS system from VPRI sounds like it checks most of those boxes. I don't think it's publicly available right now (although it was developed with NSF funding, so may eventually be).
Last week VPRI published the final "STEPS Toward the Reinvention of Programming" paper.
Although it is 2012, it had been unavailable publicly until now. A great way to catch up on how FONC ended. It was worked on by many individuals being cited as part of HARC.
Interesting on one hand, nothing new on the other.
Complexity through a few iterations of a very simple algorithm is one of the corner stones of Stephen Wolfram's "A New Kind of Science" and has independently been proven feasible by VPRI's "STEPS" project .
I had to google (again) for documentation on STEPS and it's not the document I was looking for, but one of the for me astonishing insights was that correct text flow in typesetting is just a special case of a cellular automaton. If anyone finds the document that highlights this, I'd be grateful for a link.