You can leave services.sync.prefs.sync.* prefs at their true default, those prefs specify whether to include specific prefs in syncing prefs.

You can try these prefs:

• layout.spellcheckDefault = 0 [0:disable; 1:multi-line; 2:single-line]
• ui.SpellCheckerUnderlineStyle = 0

Thanks for this. Very much appreciated.

I've reversed the services.sync.prefs settings. I did have the layout.spellcheckDefault set to 0, it turns out. I don't seem to have the iu.SpellCheckerUnderlineStyle setting, however. Is there a different title that now goes under, perhaps?

You can leave services.sync.prefs.sync.* prefs at their true default, those prefs specify whether to include specific prefs in syncing prefs. You can try these prefs:

• layout.spellcheckDefault = 0 [0:disable; 1:multi-line; 2:single-line]
• ui.SpellCheckerUnderlineStyle = 0

Thanks for this. Very much appreciated.

I've reversed the services.sync.prefs settings. I did have the layout.spellcheckDefault set to 0, it turns out. I don't seem to have the iu.SpellCheckerUnderlineStyle setting, however. Is there a different title that now goes under, perhaps?

ui.SpellCheckerUnderlineStyle is one of the many ui.* prefs that you can use to modify look and feel settings, most do not exist by default and need to be created.

• https://searchfox.org/mozilla-release/source/widget/nsXPLookAndFeel.cpp

See StyleTextDecorationStyle:

• https://searchfox.org/mozilla-release/source/layout/style/nsStyleConsts.h

ui.SpellCheckerUnderlineStyle is one of the many ui.* prefs that you can use to modify look and feel settings, most do not exist by default and need to be created.

• https://searchfox.org/mozilla-release/source/widget/nsXPLookAndFeel.cpp

See StyleTextDecorationStyle:

• https://searchfox.org/mozilla-release/source/layout/style/nsStyleConsts.h

Cool, thanks. Entirely outside of my previous experience! But I'll try things out and see what can be achieved that way. Much appreciated.

If you’re wondering how to spell check, Firefox’s default settings have your spell checker enabled. When you’ve typed a misspelled word, it will underline the misspelled word and suggest the correct word to choose. To fix misspelled words, here’s what you have to do:

Using your Firefox browser, enter text into a text box. Right-click on the misspelled word. Select the correct word from the suggested words in the menu.

Regards, James

If you’re wondering how to spell check, Firefox’s default settings have your spell checker enabled. When you’ve typed a misspelled word, it will underline the misspelled word and suggest the correct word to choose. To fix misspelled words, here’s what you have to do: Using your Firefox browser, enter text into a text box. Right-click on the misspelled word. Select the correct word from the suggested words in the menu. Regards, James

Thanks James. I'm asking how to turn off spell check entirely, however, and eliminate the red line underneath. I have no interest in robots trying to second-guess my spelling.

You can check it out in the settings section go to the language section uncheck the correct spelling setting

You can check it out in the settings section go to the language section uncheck the correct spelling setting

Thanks, but that's already been tried prior to asking the question here.

Setting ui.SpellCheckerUnderlineStyle = 0 should disable the underlining whether spell checking is enabled or not.

Setting ui.SpellCheckerUnderlineStyle = 0 should disable the underlining whether spell checking is enabled or not.

The setting it gives me is true/false, and setting it to false doesn't seem to make a difference. Perplexing.

The ui.SpellCheckerUnderlineStyle pref should be a Number pref (0-6) and not a Boolean pref (true/false). The main control pref layout.spellcheckDefault is also a Number pref (0-2).

The ui.SpellCheckerUnderlineStyle pref should be a Number pref (0-6) and not a Boolean pref (true/false). The main control pref layout.spellcheckDefault is also a Number pref (0-2).

Strange. I've got things set this way now, and it still doesn't make a difference.

extensions.spellcheck.inline.max-misspellings 0 layout.spellcheckDefault 0 services.sync.prefs.sync.layout.spellcheckDefault true services.sync.prefs.sync.spellchecker.dictionary true spellchecker.dictionary ui.SpellCheckerUnderline 0 ui.SpellCheckerUnderlineStyle 0

ui.SpellCheckerUnderline is the color of the underlining (#FF0000)

On what pages does this happen ? It should work in the text editor used on this website.

Setting layout.spellcheckDefault to 0 and ui.SpellCheckerUnderlineStyle to 0 should disable the spell checking and hide the underlining.

You can see which dictionary is selected if you right-click in a text area and open the Languages sub menu. The spelling checker is enabled if [X] "Check Spelling" in the right-click context menu has a checkmark.

You can enable or disable spell checking globally:

• Settings -> General: Language and Appearance: "Check your spelling as you type"
• https://support.mozilla.org/en-US/kb/how-do-i-use-firefox-spell-checker

ui.SpellCheckerUnderline is the color of the underlining (#FF0000) On what pages does this happen ? It should work in the text editor used on this website. Setting layout.spellcheckDefault to 0 and ui.SpellCheckerUnderlineStyle to 0 should disable the spell checking and hide the underlining. You can see which dictionary is selected if you right-click in a text area and open the Languages sub menu. The spelling checker is enabled if [X] "Check Spelling" in the right-click context menu has a checkmark. You can enable or disable spell checking globally:

• Settings -> General: Language and Appearance: "Check your spelling as you type"
• https://support.mozilla.org/en-US/kb/how-do-i-use-firefox-spell-checker

Well, this is embarrassing, but the question of where this happens is something I should have thought about earlier. The main place it happens is on Google search, which is where I'm mostly likely to be typing something on the web (rather than an on-machine email program, Excel, Word, that sort of thing). It doesn't happen here. Everything has been unchecked globally, etc., so it's probably some annoying Google test of involuntary spellcheck. It doesn't replicate on other web browsers, but it may be something specific to Google nonetheless.

In short, I'm afraid I may have wasted your time on this one by barking up the wrong tree. Probably not Firefox at all, but something specific to Google Search. Dang it. Thanks for the time spent trying to solve this, which has at least led to learning some new things about Firefox controls.