x Added trick to drag private tab to another window (with disabled multi-process mode, thanks to Dumby) (#242).
+ 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+.