https://searchfox.org/mozilla-central/rev/c07aaf12f13037c1f5a343d31f8291549e57373f/browser/components/customizableui/content/panelUI.inc.xul#87

This panel has a number of different uses. AFAICT all the strings live in browser.dtd

They could be migrated to a separate ftl file (appMenuNotifications.ftl ). We can load it on-demand using MozXULElement.insertFTLIfNeeded in https://searchfox.org/mozilla-central/rev/c07aaf12f13037c1f5a343d31f8291549e57373f/browser/components/customizableui/content/panelUI.js#738 . We should probably wait for the translations to be finished in the notification we're going to show before continuing to call openPopup().

We might then need to fix some automated tests that expect the panel to show synchronously in that case.

Hey Gijs! I'm happy to work on this if it's still available.

(In reply to danielleleb12 from comment #1)

Hey Gijs! I'm happy to work on this if it's still available.

This (and the other deps of bug 1517304) is not a great place to start, unfortunately. Please talk to the mentors of the project you're interested in to find appropriate bugs for the project you want to work on.

https://hg.mozilla.org/mozilla-central/rev/ddb852bfc987