Firefox 3 comes with a cool built-in spelling checker. If you’ve ever used, say, Google Docs ro posted a message in an online forum, you’ve probably seen it at work in the form of a red line under each misspelled work. You could right-click the word to see spelling suggestions along with the usual context-menu options).
It’s a great feature, but with a shortcoming. It doesn’t work in Web forms. But with a simple tweak to the about:config, you can get the spelling checker to work in forms too.
Open Firefox, type about:config in the address bar and hit Enter. In the Filter field, type spellcheck. Right-click layout.spellcheckDefault, and click Modify. Change the value from 1 to 2 and restart Firefox. The spelling checker should now work in most online forms.