From the about:mozilla, a noticeable improvement with Firefox 4/
Improvements to Firefox 4′s spell checker
Ehsan Akhgari writes about important changes to the spell checker in Firefox, namely that the newly patched spell checker will work with hyphenated words (it does not currently) and will work with words up to 130 characters long (current limit is 64.) As the spell checker is probably one of the features of Firefox that we all use unconsciously, this is a very welcome addition.
Excellent news! But the longest word in major dictionary regarding to Wikipedia is Pneumonoultramicroscopicsilicovolcanoconiosis
and it have only 45 letters, why Firefox needs 130 characters long support? 🙂
Moreover, I checked this word in Firefox, Google Chrome spell checker and here: http://www.spellchecker.net/spellcheck/
It doesn’t presented at all 🙂