Originally Posted by wawa
to be specific, mui4 is what morphos users have been enjoying for years while os4 users were enjoying mui3.9 which has lately been ported to amiga as well. os4 mui4 port is also rather fresh, but it is good if all the systems receive about the same standard.
Yes, that sounds so wrong at AmiKit's page and announcement. MUI4 has been the official GUI toolkit of MorphOS for over 6 years, and was only recently adopted to OS4. And AFAIK OS4 version is reverse-engineered/cloned to match in most parts the original version, but without the official support.