Allow certain add-ons/themes to not sync across browers.

[WoodwardIII]

Add a box you can uncheck on the 'Manage extension' page next to each addon/theme to disable them from syncing with other browsers on your account.

This would be useful in at least two places:

• Setting different themes in nightly so is visually obvious which Firefox is open (I daliy normal FF but use nightly for testing code)
• Only have performance add-ons were needed (eg h264ify on my old pc but not my new laptop)

Seriously Firefox devs, PLEASE add this, the lack of it is a problem for me every day, and when I switch computers I need to manually toggle about 5 things off and on just to do work (and by work I mean the all-important pastime of video watch).

[Jon]

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[Username0815]

Workaround
If youre looking for: Disable sync theme across Programs or PCs inside about:config:

Set to false:

• services.sync.prefs.sync-seen.extensions.activeThemeID
• services.sync.prefs.sync-seen.services.sync.prefs.sync.extensions.activeThemeID
• services.sync.prefs.sync.extensions.activeThemeID

Set to true:

• services.sync.addons.ignoreUserEnabledChanges

It may only work with the last one because some of the settings seem to be discontinued. I didnt want to try all cases so i disabled all of them.

Sources

• https://support.mozilla.org/en-US/questions/1372066
• https://support.mozilla.org/en-US/questions/1381032

If this disables more than just themes pls let me know

[happysmash27]

I concur!

I have a bunch of different Firefox instances on the same computer as it can get slow and overwhelming to have too many windows (dozens) and tabs (hundreds or thousands) open in the same profile. Spreading my tabs across different browser instances means I can close large swaths of them to save CPU, while still being able to open the same profile again in order to keep the structure of the tabs I had open for that project – e.g, if I decide to pause shopping for later in order to work on a Blender project, I can close my Shopping profile and open my Blender profile without losing the structure of the tabs in either one. Having every window from every project I am currently working on open is too intensive for both Firefox, and my own attention. I also find, that in my old server system with a ridiculous amount of RAM and threads but not a very fast single-core speed, Firefox is able to perform a lot better when I have multiple instances open at once instead of many things open at once in the same instance.

Having a different theme for each profile helps me keep track of which theme is for which use. Different themes help make it much more obvious which window is for which instance, to help me stay more organised. It is very annoying how hard it is to properly ensure the themes are separate for each instance.