I'm able to write new posts using Xinha4WP, but I can't seem to get it to work when editing existing posts - all I see is the default html interface (I've disabled wordpress' own rich-text editor).
Strangely, the spellchecker works even when editing, it's the interface that does not.
This seems to be a problem specific to Firefox and browsers sharing the same core; Both Firefox 2.0 and Flock(based on Firefox) have the same problems. I don't have any problems when using IE 6.0, however.