I am using Slack from snaps and Firefox from AppCenter (non-curated). I made Firefox my default browser. When I click a link in Slack it opens in Firefox but there are three problems.

  1. It doesn't open in an active window but creates a new one
  2. The new window has a strange thick black shadow [1]
  3. The new window doesn't share cookies so I am logged out of everything and I have zero extensions so I can't even use my password manager.

[1] Shadow screenshot https://i.stack.imgur.com/T1kEM.jpg

I actually don't mind the shadow or separate window that much. But I'd love to open the links in an instance of Firefox where I am already logged into various services.

How can I open the links in an instance that has all my cookies and is logged into everything?

  • Hi there! This sound more like a Firefox / snap issue to me, not an elementary OS specific one. You can also try reddit.com/r/firefox
    – Vlad
    Dec 10, 2020 at 9:26

1 Answer 1


I've found that the problem was Slack from Snap. When I installed both Slack and Firefox via AppCenter as non curated apps, it works normally. Something is not working between different stores.

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