about:config

Open about:config to change hidden settings that cannot be edited from the Options window.

All Mozilla based programs have settings that can not be changed in the options window. These hidden settings are all reveled in the about:config where anything can be changed or reset.

Compatibility: Pale Moon Thunderbird, Postbox SeaMonkey
This button is a legacy add-on, and can not be ported to Firefox 57+.

Often used with:

• Close Tab
• Return Receipt
• Work Offline
• Unread Threads
• Zoom Out