I have searched for the similar title, got a few answers which are not applicable to my case:
- Is disabling spell check systemwide still possible in Sierra? (redirects to the next link)
- Is it possible to disable spell check systemwide? (does not work post-Sierra)
I have "System settings > Keyboard > Text > Correct spelling automatically" turned off.
Many applications have their own spellchecking flag, which can be changed via "Edit > Spelling and Grammar > Check Spelling while typing".
What I would like to achieve is to disable all checkboxes under "Spelling and Grammar" menu for all applications. I believe it should be possible via something like
defaults write ..., but I have no idea what to put there.