As I just discovered & noted in https://bugzilla.mozilla.org/show_bug.cgi?id=1306425#c10 , this doesn't actually require any Firefox add-ons -- you can reproduce it in Firefox's "Certificate Viewer" UI, too.
Anyway -- I'm glad we've got a fix in the pipeline here! Thanks, Martin! ** Bug watch added: Mozilla Bugzilla #1306425 https://bugzilla.mozilla.org/show_bug.cgi?id=1306425 ** Summary changed: - Tabs in Firefox add-ons are not rendered + Tabs in Firefox dialogs are not rendered (for add-on options & Certificate Viewer) -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to ubuntu-themes in Ubuntu. https://bugs.launchpad.net/bugs/1631208 Title: Tabs in Firefox dialogs are not rendered (for add-on options & Certificate Viewer) Status in ubuntu-themes package in Ubuntu: In Progress Bug description: Tabs in the preference dialogues of Firefox add-on don't render anymore in Ubuntu 16.10. Here is the upstream bug report: * https://bugzilla.mozilla.org/show_bug.cgi?id=1306425 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ubuntu-themes/+bug/1631208/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp

