Firefox: Setting to Prevent Exiting macOS Full Screen Mode with the ESC Key

Problem

On macOS, when a Firefox window is in OS-level fullscreen (the green button), pressing the ESC key exits fullscreen.

This is inconvenient when you want to use ESC for other actions (e.g., closing a modal, closing the search bar, etc.), because you can accidentally exit fullscreen as well.

Solution

Change a setting in about:config.

Steps

1. Type about:config into Firefox’s address bar and press Enter.
2. Click “Accept the Risk and Continue.”
3. In the search bar, type browser.fullscreen.exit_on_escape.
4. Double-click the value and change it to false.

Setting value

Notes

• Even after changing this setting, you can still toggle fullscreen with the F11 key.
• You can also exit fullscreen from the macOS menu bar (View → Exit Full Screen).
• This is a different setting from the website Fullscreen API (e.g., YouTube video fullscreen).

Verified environment

• macOS
• Firefox (as of January 2025)