Just a heads up to some localizers (fr, nl, pt-PT are already in the discussion). Firefox spellchecking code fails to recognize '-' as part of a word. For Portuguese that's an important issue with Firefox (wrongly) complaining about several correct words. This is something Mozilla-specific and is not an issue with upstream Hunspell code.
This bug has been marked as 'minor'. Unfortunately it's not minor to us, and the reasoning for it to be considered 'minor' is that it occurs seldomly in English.
If your language is affected by this, please vote and/or follow the discussion on the bug:
[Bug 355178] spell checker doesn't accept "scot-free" (tokenization, Hunspell 1.2.8)
https://bugzilla.mozilla.org/show_bug.cgi?id=355178
Thanks in advance,
João Miguel Neves
PS: We also have the people that provide the spellchecking dictionary to us complaining that they're getting complaints because Firefox is broken.