About this Add-on
Still not possible to implement using WebExtensions without changes from Firefox side.
Adds private tabs.
Usage: see screenshots.
Also you can create private bookmarks to always open some links in private tabs: just prefix “private:” before URL, example: private:https://addons.mozilla.org/
In English: http://forums.mozillazine.org/viewtopic.php?t=2665169
In Russian: http://forum.mozilla-russia.org/viewtopic.php?id=58122
Source code and issues tracker: https://github.com/Infocatcher/Private_Tab
Please read about known issues before reporting bugs:
Some styles for userChrome.css/Stylish to change private tabs appearance:
Works only in Gecko 20.0 and higher (Firefox 20.0+ and SeaMonkey 2.17+) because used API doesn't exist in older versions!
See https://bugzilla.mozilla.org/show_bug.cgi?id=800193 for information about “Warning: Only internal code is allowed to set the usePrivateBrowsing attribute” in the Error Console.
[+] Added Dutch locale (nl), thanks to TonnesM (#268).
[+] Added Bulgarian locale (bg), thanks to Peyu Yovev (#270, #271, #272).
[+] Updated Arabic (ar) locale, thanks to tahani5.
[*] Better appearance of button after last tab in Firefox 57+ (for extensions.legacy.enabled = true, also introduced extensions.privateTab.fixAfterTabsButtonsAccessibility.force preference).
[*] Compatibility enhancements for Basilisk.
[x] Fixed generator function usage in Firefox 58+ (bug 1083482).
[x] Fixed string preferences in Firefox 58+ (bug 1414096).
[x] Fixed private protocol in Firefox 58+ (strange things with __defineGetter__(), nsIURI.spec is now read-only) (bug 1431204).
[x] Fixed inIDOMUtils usage in Firefox 59+, now used window.InspectorUtils (bug 1427419).
[x] Correctly handle first browser window in Firefox 60+ (browser.startup.blankWindow = true, thanks to Dumby) (bug 1336227).
[x] Fixed hotkeys hotkeys in Firefox 60+, added replacement for removed nsIDOMKeyEvent bug 1436508.
[x] Fixed accessing to DownloadsCommon.jsm internals in Firefox 57+.