disable command+alt+f shortcut
just want to disable the shortcut as I have global Mac shortcut configured for this key combo
Beyond another csschrome edit they are set shortcuts.
What does that shortcut do? (I'm a Windows person, so can't try it myself.)
If you have a system-level hotkey defined, usually that would intercept the keyboard shortcut and prevent Firefox from receiving it. I'm not sure why it isn't working on your Mac.
Look that command+option+f is used in Firefox to set focus to the location bar. I don't think that you can disable such a built-in keyboard shortcut.