Firefox has stopped insisting that there's a "u" in "neighbour", though it periodically reverts to thinking I'm British. But the Slack app can't be told otherwise. Is there some kind of system-wide setting I should be using?
I'm using the official beta.
This question: How to use American English spelling dictionary in Firefox? seems to suggest that I should remove the myspell-en-au myspell-en-gb myspell-en-za packages which I'm happy to do but I don't see myspell-en-us installed at all and at least Firefox definitely has English (United States)
When I do cat /etc/default/locale it definitely knows I'm American: LANG="en_US.UTF-8"
So is this an issue with Slack? Or is there a setting elsewhere that I should be looking at?