note that the htmlArea team jsut released version 3.0 RC1 whcih is the release tree that includes mozilla support.
I have it running on a test server you can check out:
With everything:
http://home.pumptheory.com/ha/examples/fully-loaded.html
My favourite, with tables and context menu, but no spelling or full page supprt:
http://goo:8001/ha/examples/context-menu.html
Two caveats:
1/ it has crashed my mozilla once so far - but then my mozilla does crash from time to time...
2/ the spell checker uses a perl cgi. since it's not in a /cgi-bin/ or similar segregated directory, i couldn't figure out how to get aolserver to run it. wouldn't be hard to make the it link in from there though.