I'd love to hear more about your project. I've been looking at McClim and CLOG for UI. Don't know if they support OpenGL viewports.
I agree with the "least resistance" notion. The way I've always thought about it is that Lisp is the only language that doesn't fight me when I'm using it.
I have a GUI example Knowledge Graph Navigator in my Lisp book [1] and I am separating out for a new edition the library code and the CAPI code. I also have plans to supply UIs written with McCLIM and Open Graphics. I am motivated because some readers said that having a CAPI example was useful to them. I write just for fun, and I tend to put emphasis on material where I get the most feedback.
I agree with the "least resistance" notion. The way I've always thought about it is that Lisp is the only language that doesn't fight me when I'm using it.