The spell checker word library is not at all definitive no 'Microsoft' for starters. When you have quite a lot of text you can't ascertain what word it is attempting to correct as the correction menu does not appear in the correct place and my words for correction are not appearing yellow. I have a way round this however I use a third party IE spell checker app that works brilliantly.
Secondly I have just joined this forum so maybe this has already been discussed but why am I forced to reason an edit???
One thing I like about the new forums as compared to the old is that the spell-checker in my Mozilla browser (SeaMonkey) works in it automatically. Mis-spelled words are underlined in red, and my personal dictionary is applied to the content. Just like in the newsgroups :-).
So I see no need for me to use the Ajax spell-checker.