I've been looking for something like this all morning. The only thing I found close to making a custom browser UI is Mozilla's Chromeless SDK which is in alpha stages. <a href="http://github.com/mozilla/chromeless" rel="nofollow">http://github.com/mozilla/chromeless</a><p>Anybody knows anything else other than taking Gecko or webkit and doing it the hard way?
I like to keep my eye on these browsers. Conkeror got very close to being the sort of browser I would like to have but was just a little bit too slow compared to Webkit based browsers.<p>One thing that puzzles me about this though: why lua when you have access to JS engines? Would I have to use two extension languages to write a plugin which touches a webpage and the chrome?