@jsit @jensimmons My greatest failure of my time working for Mozilla is that I *could not find* the code that actually does line breaking and therefore I was unable to even try implementing Knuth-Plass line breaking.

It might not be too slow! Nobody's tried it because everyone thinks it'd be too slow, but we don't know for sure! Except also nobody has tried it because nobody can figure out what to change. nsLineBreaker *sounds* like it does line breaking, right? Nope.