In System Preferences, I have D set to Enter Full Screen and Exit Full Screen. I have been using these shortcuts for close to a decade now, and I'm really not interested in relearning them.

enter image description here

Unfortunately, D is also Firefox's built-in shortcut for creating a new bookmark. Unlike most Mac apps I've used, Firefox's built-in shortcut appears to take precedence over my custom one.

How can I make Firefox to respect my D shortcut for entering and exiting fullscreen?

(Small note: I happen to be on a very old version of macOS, specifically 10.9 Mavericks. I don't think this is relevant to the question.)

  • Does it have a matching menu entry? [I don't have FF to check] Safari, for instance has an entry for 'Add Bookmark…' which could be overridden with a junk command, hopefully relinquishing control to your global command.
    – Tetsujin
    Commented Oct 20, 2019 at 14:35
  • @Tetsujin Yes, there is a "Bookmark This Page" menu entry, which by default the menu bar says isn't assigned to a shortcut, even though it is. Adding a shortcut for that entry had no affect on ⌘D. Commented Oct 20, 2019 at 16:21
  • To be certain, add the exact text [inc ellipsis not three full stops, if appropriate] to the App itself, not All Apps, in Shortcuts & assign it some junk key combi. If it exists as a menu item, it can be overridden. I have dozens of answers on AD related to this - apple.stackexchange.com/search?q=user%3A85275+key+command
    – Tetsujin
    Commented Oct 20, 2019 at 16:29
  • @Tetsujin I'm pretty sure I did? This is set in System Preferences i.postimg.cc/P5vqG9G1/Screen-Shot-2019-10-20-at-10-27-13-AM.png and it shows up in Firefox's Menu Bar: i.postimg.cc/Gh5p5rfc/Screen-Shot-2019-10-20-at-1-27-41-PM.png. And, pressing ⌃⌥⇧⌘F12 does create a new Bookmark now... but, so does ⌘D. Commented Oct 20, 2019 at 17:32
  • 1st pic is possibly not the one you meant, but 2nd show the result - tbh, at that point I'm stuck… should work but doesn't :\
    – Tetsujin
    Commented Oct 20, 2019 at 17:37

2 Answers 2


Unfortunately, this is a long-running, documented bug in Firefox. https://bugzilla.mozilla.org/show_bug.cgi?id=1333781

You can add custom keyboard shortcuts which Firefox does not already use, but you cannot remap a shortcut that is built into Firefox.


This is a known issue in Firefox.

I use BetterTouchTool, a commercial app, to remap command-D to another purpose in Firefox. It intercepts the keystrokes before Firefox gets them. You can assign various other actions, including different keyboard shortcuts, or an "Enter fullscreen" action. There may be other similar commercial apps, but I haven't tested them.

You could try using the free Karabiner Elements app to globally remap command-D to control-command-F (the default for "Enter Full Screen", in most apps) instead of using System Preferences. It works on a lower level. It's possible to use Karabiner for an application-specific remapping, but it's more complicated to set up.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .