Bug 899276 and bug 956826 removed the ability to restore tabs in private windows or permanent private browsing mode. We should revert that change, it makes sense to think of the whole private browsing window as a private session that is gone once the windows is closed. As a private tab in a non-private window is a mini version of that private session I think it makes sense to not put it into the list of closed tabs and just discard it. At the same time when closing a non-private window that contains private tabs we should remove all private tabs. Even if private tabs are unsupported I feel like we should make the right decision here to not expose private data by potentially careless add-ons.

Asking for UX to review the proposed changes as well.

Try builds to test the behavior are here: https://ftp.mozilla.org/pub/mozilla.org/firefox/try-builds/ttaubert@mozilla.com-537f9a78b95a/

Comment on attachment 8362123 [details] [diff] [review] 0001-Bug-961380-Should-be-able-to-undo-closing-tabs-in-pr.patch Review of attachment 8362123 [details] [diff] [review]: ----------------------------------------------------------------- Does what it is supposed to do, both with and without the add-on.

Try looks good btw: https://tbpl.mozilla.org/?tree=Try&rev=537f9a78b95a

Comment on attachment 8362123 [details] [diff] [review] 0001-Bug-961380-Should-be-able-to-undo-closing-tabs-in-pr.patch Review of attachment 8362123 [details] [diff] [review]: ----------------------------------------------------------------- Looks good, thanks. ::: browser/components/sessionstore/src/PrivacyFilter.jsm @@ +95,5 @@ > + * @param browserState (object) > + * The browser state for which we remove any private windows and tabs. > + * The given object will be modified. > + */ > + filterPrivateWindowsAndTabs: function (browserState) { Good idea.

Thank you, Tim!