Well MUI has been further developed, ported to C (from 68k-asm) and
pushed to version 4 by Ralph Schmidt for use with MorphOS.
"Thanks" to Strunzi's non-exclusive licencing these changes will
also be available for OS4 if and when Hyperion manages to compile
them. (no flame-bait, just factual as it is not running yet (AFAIK))