FirefoxSpellChecker
This option enables Firefox's built-in spell checker while typing. Even if word suggestions will not appear in the FCKeditor context menu, this feature is useful to quickly identify misspelled words.
Code:
FCKConfig.FirefoxSpellChecker = true ;
The BrowserContextMenuOnCtrl setting may be used in combination to make it possible to show the default context menu, containing misspelled words.