Manual:Hooks/GetPreferences

Details

 * $user: User whose preferences are being modified.
 * &$preferences: Preferences description array, to be fed to an HTMLForm object

Tabs and sections
The  array key specifies which tab and section of  contains your preferences. If your  value is foo/bar, this means your preference will appear on the foo tab (named by system message  ) within the bar section (named by system message  ). If no such tab or section exists, it is created automatically.

Supported types
The  can take on various values found in class   in the file.

Default preferences
To set the default value for a preference (i.e. the value that is set for a new user that hasn't customized their preferences yet), add the setting to the $wgDefaultUserOptions global variable. Use the same key name as you use for $preferences in the hook.