What do you do about misspelling words in text boxes? Well, you use the built-in Firefox spell check feature. However, by default it does not work with ALL text fields. That can simply be rectified though your about:config settings.
Just type in about:config into your address bar to get started. Next, into the filter text box, type in layout.spell. That should bring up the preference name layout.spellcheckDefault. Right-click it, and then select “Modify”. Change the 1 (default value) to 2 and you should be all set.
Firefox’s built in spell check will now check all text fields, no matter where or how they are used on the web site in question.