At some point in the past, Firefox remembered correctly the language I had set for the inline spell checker for each container tab. So, if I had German and English dictionaries installed, and had my German Twitter open in one container, and the English in the default/no container setting, I could have them both set to the correct language I usually tweeted in.

Some versions ago, like in the mid-seventies range, Firefox lost that ability. The language setting is now global across containers, posing an inconvenience for me and possibly other multilingual users.

To reproduce:

1. Install more than one language dictionary, like English and German, English and French, or English and Spanish. Or any other combination.
2. Open the same web app, like Twitter, with different accounts, in two container tabs.
3. Start a new tweet, and set each one's spelling language, by right-clicking in the text box and choosing the language from the sub menu.

Expected: You should be able to set it individually for each container.
Actual: The checked language always follows the last setting you made in any container.

hi, i tried to find a regression range with the help of mozregression, but couldn't find any good version with those steps to reproduce going back the past two years (i got the same results when i tested with permissions.isolateBy.userContext enabled too).

are there any more factors or settings in your setup that could influence the outcome?

I don't know of any factors that could have influenced this. I know that at some point it worked, and when I tried it later, I noticed that the per container setting was no longer being remembered.

The severity field is not set for this bug.
:dveditz, could you have a look please?

For more information, please visit auto_nag documentation.

I don't know that this was ever a feature of containers. If it was, I don't know if it's something that was remembered in the core feature (appropriate for a bug here) or something in the Extension front-end (bug would need to be moved to a github issue).

Maxx: can you help direct this bug to the right folks?

Sure can. I'll reach out to :groovecoder and follow up.

We never designed this into the add-on. :baku - do you know if we ever stored preferred language by userContextId ?

We do not support this feature. We discussed it in the past, but the code has never been written.

I imagine this would have to be implemented in the Extension, which tracks issues in github. Might be more successfully moved there. Removing the regression keyword because we can't imagine how this ever worked -- at least not based on Containers. Maybe the spelling checker itself had heuristics based on the declared language of the page contents?