I created the shiftcommandn shortcut for Firefox in Syst Prefs to match other browsers' behavior.

syst prefs

It registers in the Firefox Menubar.


But pressing the shortcut opens a new non-private window, and it loads there the first item in my "Top Sites".

I imagine I could create another shortcut to override this behavior, but what is this behavior? I don't see anything highlighted in the Firefox Menubar when I hit the shortcut. Or might there be another solution (other than using a different shortcut to open new private windows)?

Problem exists on both Mojave and High Sierra. Default Firefox shortcut (shiftcommandp) still opens a new private window.

  • If you remove your shortcut - does Shift - Command - P open a private window? If that goes to the private landing page and then the Shift - Command - N goes back to new window, this would be a bug with the Firefox app since it's up to the app to handle the keys properly when the shortcut is handed off by the OS. You could mess with the N key to change it to Z or S to verify that it's the app ignoring the menu being pressed and instead parsing the keys (potentially).
    – bmike
    Commented Nov 17, 2018 at 19:34
  • related apple.stackexchange.com/questions/338704/…
    – pkamb
    Commented Nov 17, 2018 at 19:46

1 Answer 1


This has been a known Mac Firefox bug for years and years. Because Firefox is not truly a native macOS app, it carries over odd behaviors, one of which being that you cannot fully override its pre-defined keyboard shortcuts.

Firefox 55 addressed this partially as Mozilla bug #429824, which allowed new keyboard shortcuts to be created via System Preferences. Overriding existing shortcuts like "New Private Window" or "Paste" or whatever is still not completely possible, but progress (or lack thereof) is being tracked by Mozilla bug #1333781. In any case, you get all sorts of weird, undefined behavior if you try to override those shortcuts anyway.

Before the great extension purge in Firefox 57, Firefox extensions like keyconfig let you work around the problem by remapping those shortcuts within Firefox itself. After Firefox retired all legacy extensions, this once again became impossible.

Since Firefox 57 (being so annoyed by some of its default, un-Mac-like shortcuts) I've compiled Firefox from source code just so I could patch its keyboard shortcut configurations. Not something I'd recommend to most people, but it is one potential workaround until the bug is fixed upstream.

  • 2
    @jtheletter Firefox is built to be cross-platform and has its own UI framework, so it doesn't use parts of the native Cocoa framework that makes up the look-and-feel of macOS. So lots of things that Cocoa apps get for free (like the ability to have its shortcuts overridden via System Preferences) they have to implement manually. This is also expressed in the rest of its UI, which often behaves just slightly differently from "true" macOS apps (e.g. kilianmuster.com/firefox-the-good-bad-and-ugly ). It's gotten much better over the years though.
    – vykor
    Commented Nov 24, 2018 at 16:42
  • 2
    FWIW, I'm an Alfred user and I was able to fix this by creating an Alfred workflow that triggers on Cmd-Shift-N and emits Cmd-Shift-P but only when Firefox is the active application. Commented Oct 14, 2019 at 20:41
  • @apaidnerd Alfred users here too. Any chance you'd share your workflow please?
    – snowbound
    Commented Aug 12, 2021 at 2:11

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