In Mozilla Firefox the default spell checking function only checks for multi-line text boxes. However it is also possible to get Firefox to spell-check single line text boxes.
This option doesn’t appear in the standard Tools and Options so we’re going to edit some hidden firefox preferences. To do this open the Mozilla Firefox browser and enter about:config into the url bar at the top of the screen, then press enter.
If this is the first time you have been to these preferences you will receive a security warning promting you before going further – aslong as you promise to be careful you can continue!
Lots of options… lets make use of the filter provided to find the right one. You should see a flashing indicator in a textfield called Filter: at the top of your screen. Type spellcheckd into the Filter: textfield and that should narrow us down to just the one option as show below.

Mozilla Firefox Spellcheck All Fields
Double-clicking on the field lets you change the value. By default the value is set to 1
Selecting one of the following values will provide the following behaviour…
- Disable spell checker
- Specll check multi-line text boxes only (default)
- Spell check all text boxes
Choose the option which is right for you and then close the about:config tab.




