Is there a way to have Firefox's spellcheck check the spelling in all text input fields? [duplicate]
Solution 1:
Type about:config in the address bar, agree to the warning if displayed, then set the value of layout.spellcheckDefault to 2.
0: Disable spellchecker.
1: Enable spellchecker for multi-line controls (e.g., <textarea>s). (Default in Firefox and SeaMonkey)
2: Enable spellchecker for multi-line controls and single-line controls. (Default in Camino)