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About:config entries

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-[[Category:Configuration (Firefox)]] [[Category:Configuration (Thunderbird)]] [[Category:Configuration (Mozilla Suite)]]+[[Category:Configuration]]

Revision as of 12:05, 19 September 2005

This is not the place to modify your about:config settings. This is a reference to the entries in about:config.

about:config is a list of preferences that you can change. This article is meant to be a partial documentation of those preferences. Alternative lists can be found at the Preferential project, Mozilla's networking documentation, and Mozilla's embedding documentation. See also Editing configuration and User.js file.

Many of the entries that appear in Firefox will also apply to Mozilla Suite and vice versa.

Note: Spaces between the dots in preference names exist purely for word-wrapping. They are actually not present and should not be thought as so. Editors of this page must take care to follow this convention in order to not force users to horizontally scroll this article.

Contents

Accessibility.*

Name Type Meaning of Values
accessibility. accesskeycausesactivation Boolean True (default): Using an accesskey will have the same effect as clicking on the applicable element with the mouse.
False: Using an accesskey will only focus the applicable element.
accessibility. browsewithcaret Boolean True: A caret is present in the browser window to use to select text with the keyboard.
False (default): No caret is present.
This can be toggled using the [F7] key.
accessibility. disablecache Boolean True: Disable caching in the MSAA implementation
False (default): MSAA cache is active
accessibility. disableenumvariant Boolean True: Disable MSAA calls to IEnumVARIANT
False (default): IEnumVARIANT support is active
accessibility. tabfocus Integer Determines which web page elements can gain focus when [Tab] key is pressed.
1 (default in OS X): Text field form controls only
2: All form controls except text fields
3: All form controls
4: Hyperlinks and hyperlinked images
7 (default): All form controls and hyperlinks
Note: In Firefox 1.5 on Mac OS X, the browser's behavior is determined by the "Full keyboard access" system preference unless this preference has been user-set (see bug 187508).
accessibility. tabfocus_applies_to_xul Boolean True (default in Mac OS X): Allows XUL elements to gain focus from [Tab] according to accessibility.tabfocus (see bug 277516).
False (default everywhere else): Opposite of the above
accessibility. typeaheadfind Boolean True: Activates Find As You Type.
False (default): Disables Find As You Type.
Note: In Firefox, this can be changed via "Tools → Options → Advanced → Accessibility → Begin finding when you begin typing"
accessibility. typeaheadfind. autostart Boolean True (default): Find As You Type will start automatically when typing starts and a form control like a text area or text box does not have focus.
False: Find As You Type will only start when / is pressed for any word and when ' is pressed for link searching.
accessibility. typeaheadfind. enablesound Boolean True (default): Find As You Type will play a sound when the typed in search phrase is not found.
False: Find As You Type will not play any sounds.
accessibility. typeaheadfind. enabletimeout Boolean True (default): Find As You Type will end after a set time if no keys are pressed.
False: Find As You Type will not end due to a timeout. To end a search use the escape key.
accessibility. typeaheadfind. flashBar Integer 0: Don't flash the Find Toolbar when a result is found
1: Flash the Find Toolbar's search field when a result is found
Note: As of Firefox 1.0, this feature is sketchy at best and nonfunctional at worst.
accessibility. typeaheadfind. linksonly Boolean True: Find As You Type will only search links.
False (default): Find As You Type will search all the text.
accessibility. typeaheadfind. soundURL String The sound to play when Find As You Type does not find a match.
(filename): .wav file to play for the error sound
default (default): The default sound
beep: System beep
accessibility. typeaheadfind. startlinksonly Boolean True: When finding links, the search will only match links from the beginning of the link's text.
False (default): The search will match any part of a link's text.
accessibility. typeaheadfind. timeout Integer The number of milliseconds that Find As You Type will wait between key presses before ending an active search. Default value is 5000.
accessibility. usebrailledisplay String Specifies the Braille display module to use. Default value is an empty string.
Note: Currently unused. Planned for future use.
accessibility. usetexttospeech String Specifies the text-to-speech module to use with the browser (e.g. "ViaVoice"). Default value is an empty string.
Note: Currently broken.
accessibility. warn_on_browsewithcaret Boolean True (default): You will be prompted to confirm enabling caret browsing.
False: Opposite of the above.

Advanced.*

Name Type Meaning of Values
advanced. always_load_images Boolean Pref removed (unused). Holdover from Netscape 4.x (then general.always_load_images). Default value is true.
advanced. mailftp Boolean True: Use a specified email address (the value in network.ftp.anonymous_password) as the password for anonymous FTP servers
False (default): Send default "mozilla@example.com" for password
advanced. system. supportDDEExec Boolean Previously used (before Firefox 0.9) to open links from external sources as tabs in a single window. Currently deprecated in favor of preferences under "Tools → Options → Advanced → Tabbed Browsing". Default value is true.

Alerts.*

Note: These apply to the "Downloads Complete"- and "Updates Available"-style alerts, not regular JavaScript alert() dialogs.

Name Type Meaning of Values
alerts. height Integer Height in pixels of the alert box. Default value is 50.
alerts. slideIncrement Integer How many pixels to move per step when "sliding". Default value is 1.
alerts. slideIncrementTime Integer How many milliseconds per step of "slide" movement. Default value is 10.
alerts. totalOpenTime Integer How many milliseconds to show the alert. Default value is 4000.

App.*

Name Type Meaning of Values
app. build_id String Pref to be removed (obsolete). Previously: Date of build in YYYYMMDD format
app. extensions. version String Pref removed. Previously:
Browser version given to extensions to check for compatibility
app. id String Pref to be removed (obsolete). Previously: The GUID corresponding to the program. Default value for Firefox is {ec8030f7-c20a-464f-9b0e-13a3a9e97384}.
app. update. autoInstallMode Integer If automatic background update downloads are enabled, determines how to treat the update when the download is complete.
0 (default): Install update without prompting
1: Prompt before installing update
2: Prompt before doing anything
Note: Firefox 1.5 and above only.
app. update. autoUpdateEnabled Boolean True (default): Periodically check update.mozilla.org in the background for updates to the browser
False: Disable all checks for browser updates
Note: In Firefox, this can be changed via "Tools → Options → Advanced → Software Update → Periodically check for updates to Firefox"
app. update. enabled Boolean True (default): Allow updates to the browser
False: Disable browser updates
Note: Probably deprecated in favor of app.update.autoUpdateEnabled
app. update. incompatible. mode Integer Determines when to skip the "extensions/themes incompatibility" alert
0 (default): If there are updates available to newer versions of installed addons that resolve the incompatibilities
1: If there are VersionInfo updates available to installed addons that resolve the incompatibilities, not newer versions.
app. update. interval Integer Determines time between checks for application updates.
In Firefox 1.0.x and below, default value is 86400000 (milliseconds in 1 day).
In Firefox 1.5 and above, default value is 86400 (seconds in 1 day)
app. update. lastUpdateDate Integer Time of last update in UNIX epoch format (seconds since 1970-01-01)
app. update. logEnabled Boolean True (default in nightlies): Log activity of update service to file
False: Disable logging
Note: Nightlies only.
app. update. nagTimer. download Integer Time in seconds before prompting the user to download a new version that is available. Default value is 86400 (1 day).
app. update. nagTimer. restart Integer Time in seconds before prompting the user to restart to install the latest downloaded update. Default value is 1800 (30 minutes).
app. update. performed Boolean True: Browser updates have been installed this session
False (default): No browser update has been performed this session
app. update. timer Integer Milliseconds between checks for all registered update-related timers. Default value is 600000 (10 minutes).
Note: Firefox 1.5 and above only.
app. update. updatesAvailable Boolean True: The update manager has found updates
False (default): There are no updates to download or install
app. update. url String URL for browser update notification. Default value is localized from chrome://mozapps/locale/update/updates.properties.
app. update. url. manual String A URL the user can browse to manually if the update service fails. Localized by default from chrome://mozapps/locale/update/updates.properties.
app. update. url. override String User-settable URL to override app.update.url for testing purposes. Localized by default from chrome://mozapps/locale/update/updates.properties.
app. version String Pref to be removed (obsolete). Previously: Version number

Bidi.*

Name Type Meaning of Values
bidi. browser. ui Boolean True: Allows the browser interface to use a bi-directional language set
False (false): Opposite of the above
bidi. characterset Integer How the browser determines the character set to use
1 (default): Document-specified character set
2: Default character set
bidi. controlstextmode Integer How controls are used
1 (default): Logical
2: Visual
3: Container
bidi. direction Integer Select direction of text
1 (default): Left-to-right
2: Right-to-left
bidi. numeral Integer How numerals are displayed
0 (default): Nominal numerals
1: Regular context numerals
2: Hindi context numerals
3: Arabic numerals
4: Hindi numerals
bidi. support Integer Select provider of bi-directional support
1 (default): Mozilla
2: OS
3: Disable
bidi. texttype Integer Type of text
1 (default): Charset
2: Logical
3: Visual

Browser.*

Name Type Meaning of Values
browser. active_color String The default color for active links as a hex code. Default is #EE0000.
browser. anchor_color String The default color for links as a hex code. Default is #0000EE
Note: In Firefox, this can be changed via "Tools → Options → General → Fonts & Colors → Unvisited Links".
browser. backspace_action Integer Determines the behavior of the backspace key
0: Goes back in history
1: Acts as Page Up
2 (and above): Does nothing
Note: Mozilla Suite only (see bug 301248)
browser. blink_allowed Boolean True (default): Use of the blink tag or CSS's text-decoration: blink will result in blinking elements.
False: Blinking is disabled.
browser. bookmarks. added_static_root Boolean Keeps track of whether a root folder for system (imported) bookmarks has been created in bookmarks.html.
True: The root folder has been created
False (default until import complete): Create the root folder (unless we're using dynamic bookmarks - browser.bookmarks.import_system_favorites), and then set this pref to true.
browser. block. target_new_window Boolean True: Links with target set to _blank will open in the current tab instead of a new window.
False: Links with target set to _blank will open in a new window.
Note: No longer in use. Use browser.link.open_newwindow instead.
browser. bookmarks. file String The full path and filename of your bookmarks file (bookmarks.html). In Windows, the path separator must be two backslashes (e.g. "C:\\Path\\To\\bookmarks.html") if the value is being set in user.js or prefs.js instead of within about:config
browser. bookmarks. import_system_favorites Boolean Determine the system bookmark strategy.
True: Enable a "live view" of system bookmarks which is read-only
False (default): Opposite of above.
Note: Setting this to "true" will prevent "Imported IE Favorites" folder from being deleted where applicable (see bug 22642).
browser. bookmarks. livemark_refresh_seconds Integer The number of seconds between Live Bookmark checks. Values under 60 are assumed to be 60; the default is 3600 (1 hour).
browser. bookmarks. restore_default_bookmarks Boolean True: The original bookmarks.html file is missing or corrupted; retrieve one of the dated backups
False (default): Do not perform bookmarks restoration
Note: Firefox 1.5 and above only
browser. bookmarks. sort. direction String The order in which to sort bookmarks in the Bookmarks Manager
descending (default): Unsorted
natural: Alphabetically, A-Z
ascending: Alphabetically, Z-A
Note: In Firefox, this can be changed via "Bookmarks → Manage Bookmarks... → View"
browser. bookmarks. sort. resource String The RDF source to use when sorting the bookmarks in the Bookmarks Manager
rdf:http://home.netscape.com/NC-rdf#Name (default): by bookmark name
rdf:http://home.netscape.com/NC-rdf#URL: by URL
rdf:http://home.netscape.com/NC-rdf#ShortcutURL: by bookmark keyword
rdf:http://home.netscape.com/NC-rdf#Description: by description
rdf:http://home.netscape.com/NC-rdf#BookmarkAddDate: by bookmark creation date
rdf:http://home.netscape.com/WEB-rdf#LastModifiedDate: by bookmark modification date
rdf:http://home.netscape.com/WEB-rdf#LastVisitDate: by date of last visit
Note: In Firefox, this can be changed via "Bookmarks → Manage Bookmarks... → View"
browser. cache. check_doc_frequency Integer How often to check the remote page for a newer version than what might be in the cache
0: Check once per browser session
1: Check every time I view the page
2: Never check (always use cached page)
3 (default): Check when the page is out of date (automatically determined)
browser. cache. disk. capacity Integer Amount of disk space allowed for the browser's cache (in KB). Default is 50000.
Note: In Firefox, this can be changed via "Tools → Options → Privacy → Cache"
browser. cache. disk. enable Boolean True (default): Use disk cache, up to capacity specified in browser.cache.disk.capacity
False: Disable disk cache (same effect as setting browser.cache.disk.capacity to 0)
browser. cache. disk. parent_directory String Full path to the directory used for storing the browser's cache. In Windows, the path separator must be two backslashes (e.g. "C:\\Path\\To\\Cache") if the value is being set in user.js or prefs.js instead of within about:config
browser. cache. disk_cache_ssl Boolean True: Cache content received via SSL (security risk!)
False (default): Do not cache content received via SSL
Note: See bug 205921 for more information
browser. cache. memory. capacity Integer Determines how the browser uses RAM for cache.
-1 (default): Automatically set size of capacity as a percentage of physical RAM
0: disables the memory cache device entirely
(n): Set the maximum RAM used to n KB.
browser. cache. memory. enable Boolean True (default): Use memory cache, up to capacity specified in browser.cache.memory.capacity (if set); otherwise, use a percentage of physical RAM (see bug 105344)
False: Disable memory cache (same effect as setting browser.cache.memory.capacity to 0)
browser. chrome. favicons Boolean True (default): Load and display "favicons" residing in the current page's site root directory
False: Opposite of the above
Note: This should be set to the same value as browser.chrome.site_icons for legacy reasons.
browser. chrome. image_icons. max_size Integer If an image's height or width is greater than this number (in pixels), the image will not have a thumbnail placed in its tab (or the Location Bar). Setting it to 0 will prevent thumbnails from being used altogether. The default value is 1024 pixels.
Note: Firefox 1.5 and above only.
browser. chrome. load_toolbar_icons Integer 0 (default): Never load site icons/favicons when displaying bookmarks in menus (overrides browser.chrome.site_icons)
1: Load site icons/favicons when they've been cached
2: Always load site icons/favicons
browser. chrome. site_icons Boolean True (default): Load and display site icons specified by link element(s) in the web page
False: Opposite of the above
Note: This should be set to the same value as browser.chrome.favicons for legacy reasons.
browser. chrome. toolbar_style Integer Set toolbar style for browser
0: Pictures Only
1: Text Only
2 (default): Pictures and Text
browser. chrome. toolbar_tips Boolean Determines tooltip behavior for chrome elements.
True (default): Show tooltips for toolbars and bookmarks. Display the name and URL for bookmarks
False: Hide tooltips for chrome elements
browser. chromeURL String Location of browser's UI chrome; launched at browser startup. Default value is chrome://browser/content/
browser. display. background_color String The default color for the background of browser content as a hex code. This affects blank tabs, web pages whose backgrounds are not explicity set, and XUL error pages. Default value is #FFFFFF.
Note: In Firefox, this can be changed via "Tools → Options → General → Fonts & Colors"
browser. display. focus_background_color String The default color for the background of focused elements as a hex code. Default value is #117722. Requires that browser.display.use_focus_colors be true
browser. display. focus_ring_on_anything Boolean True: Display the focus ring (normally only shown on links) on anything
False (default): Display the focus ring on links only
browser. display. focus_ring_width Integer Determines the display of the focus ring around focused elements.
0: Hide focus ring
1 (default): Dots around focused elements will be displayed with a 1 pixel border
(n): Display dots with a width of n pixels around focused elements
browser. display. focus_text_color String The default color for the text of focused elements as a hex code. Default value is #ffffff. Requires that browser.display.use_focus_colors be true
browser. display. force_inline_alttext Boolean True: Force broken images' alt text to be displayed inline
False (default): Show an icon if rendering in Quirks Mode and there is no alt text, or if rendering in Quirks Mode and the image has a size specified.
browser. display. foreground_color String The default color for the foreground of browser content as a hex code. This affects web pages whose text colors are not explicity set and XUL error pages. Default value is #000000.
Note: In Firefox, this can be changed via "Tools → Options → General → Fonts & Colors"
browser. display. normal_lineheight_calc_control Integer Determine method of calculating line-height (leading) in layout
-1: Uninitialized
0: Don't include external leading
1: Use what the font vendor provides
2 (default): Compensate leading if vendor's leading is insufficient
browser. display. screen_resolution Integer DPI of display device. Affects CSS absolute length units (e.g. pt, mm).
-1: Unable to determine the resolution (assume preference is not set)
0: Force use of operating system's logical resolution
(n): Assume screen DPI of n. Default value is 96.
Note: In Firefox, this can be changed via "Tools → Options → General → Fonts & Colors → Display Resolution"
browser. display. show_image_placeholders Boolean True (default): Show placeholders while image is loading
False: Opposite of above
browser. display. use_document_colors Boolean True (default): Allow documents to specify colors to use
False: Opposite of above
Note: In Firefox, this can be changed via "Tools → Options → General → Fonts & Colors → Always use my colors"
browser. display. use_document_fonts Integer 0: Never use document's fonts
1: Allow documents to specify fonts to use
2: Always use document's fonts (deprecated)
Note: In Firefox, this can be changed (between 0 and 1) via "Tools → Options → General → Fonts & Colors → Always use my fonts"
browser. display. use_focus_colors Boolean True: Set colors on focused items according to preferences
False (default): Do not set colors on focused items
browser. display. use_system_colors Boolean True: Use colors specified by OS to display documents
False (default): Opposite of above
Note: In Firefox, this can be changed via "Tools → Options → General → Fonts & Colors → Use system colors"
browser. dom. document. all. disabled Boolean True: Disables emulation of IE's document.all collection
False (default): Enable undetectable document.all support in quirks mode (see bug 248549)
browser. dom. global_scope_pollution. disabled Boolean True: Disable the more agressive emulation of IE's "IDs directly accessible in the global scope" behavior.
False (default): Automatically add IDs to the global (window) scope in quirks mode.
browser. dom. window. dump. enabled Boolean True: Enable JavaScript dump() output
False: Opposite of the above
browser. download. defaultFolder String Holds the path of the default download directory determined from browser.download.folderList. Not set by default; set after the user configures their download options.
browser. download. dir String The last directory used for saving a file from the "What should (browser) do with this file?" dialog.
browser. download. downloadDir String Determines the directory to download to when browser.download.useDownloadDir is false. Appears to mirror browser.download.dir.
browser. download. folderList Integer Which of several internally-specified locations to use for the default download directory
0 (default): the desktop
1: the downloads folder
2: the last folder specified for a download
Note: In Firefox, this can be changed via "Tools → Options → Downloads → Download Folder → Save all files to this folder"
browser. download. hide_plugins_without_extensions Boolean True (default): In the Download Actions dialog, remove entries where no file extensions are associated with a plugin.
False: Opposite of the above.
browser. download. lastDir String Path to the last directory used for a download via "Save As."
browser. download. manager. alertOnEXEOpen Boolean True (default): warn the user attempting to open an executable from the Download Manager
False: display no warning and allow executable to be run
Note: In Firefox, this can be changed by checking the "Don't ask me this again" box when you encounter the alert.
browser. download. manager. closeWhenDone Boolean True: Close the Download Manager when all downloads are complete
False (default): Opposite of the above
Note: In Firefox, this can be changed via "Tools → Options → Downloads → Download Manager → Close the Download Manager when all downloads are complete"
browser. download. manager. flashCount Integer Number of times to flash the Download Manager's taskbar entry when the DM is not in the foreground. Set to 0 to disable flashing. Default value is 2.
browser. download. manager. focusWhenStarting Boolean True: Set the Download Manager window as active when starting a download
False (default): Leave the window in the background when starting a download
browser. download. manager. openDelay Integer If a download takes less than this number of milliseconds to complete, do not open the Download Manager window. Default value is 0 (always show Download Manager window).
browser. download. manager. retention Integer When to remove downloaded files' entries from the Download Manager
0: Upon successful download
1: When the browser exits
2 (default): Manually
Note: In Firefox, this can be changed via "Tools → Options → Privacy → Download Manager History"
browser. download. manager. showAlertInterval Integer Number of milliseconds after downloads complete to show the "completed" alert. Default value is 2000.
browser. download. manager. showAlertOnComplete Boolean True (default): popup window at bottom right corner of the screen will appear once all downloads are finished.
False: the popup window will not appear.
browser. download. manager. showWhenStarting Boolean True (default): Show Download Manager window when a download begins
False: Opposite of the above
Note: In Firefox, this can be changed via "Tools → Options → Downloads → Download Manager → Show Download Manager window when a download begins"
browser. download. manager. useWindow Boolean True: Use the Download Manager window for downloads
False: Opposite of the above
Note: In Firefox, this is effectively the same as setting browser.download.manager.showWhenStarting to false; the Download Manager is used for downloads regardless of the setting
browser. download. save_converter_index Integer The format to save web pages in
0: Web Page (Complete)
1: Web Page (HTML Only)
2: Text
Note: In Firefox, this setting is remembered from the option you choose in the Save As dialog.
browser. download. show_plugins_in_list Boolean True (default): In the Download Actions dialog, display actions and filetypes associated with installed plugins.
False: Opposite of the above.
browser. download. useDownloadDir Boolean True (default): Without asking a location, download files to the directory specified in browser.download.folderList
False: Ask where to save every file
Note: In Firefox, this can be changed via "Tools → Options → Downloads → Download Folder → Ask me where to save every file"
browser. enable_automatic_image_resizing Boolean True (default): When viewing an image not in a web page, the image will be resized to fit in the browser window if it is too large for the browser window. The image can be shown in its real size by left clicking on it.
False: Images are always shown in their real size.
Note: In Firefox, this can be changed via "Tools → Options → Advanced → Multimedia → Resize large images to fit in the browser window"
browser. feedview. articleLength Integer Pref removed. Previously:
The number of words per feed item to display. Default value is 50.
Note: Feedview functionality was present for only a short while prior to Firefox 1.5 Beta.
browser. feedview. reloadInterval Integer Pref removed. Previously:
Determines how often in seconds to reload the currently rendered feed. Default value is 0 (never reload).
Note: Feedview functionality was present for only a short while prior to Firefox 1.5 Beta.
browser. feedview. showBar Boolean Pref removed. Previously:
True (default): Display the options settings in feed view.
False: Opposite of the above
Note: Feedview functionality was present for only a short while prior to Firefox 1.5 Beta.
browser. feedview. showImage Boolean Pref removed. Previously:
True (default): Display images embedded in feed items in-line.
False: Opposite of the above.
Note: Feedview functionality was present for only a short while prior to Firefox 1.5 Beta.
browser. feedview. showMenu Boolean Pref removed. Previously:
True (default): Display a menu alongside rendered feeds with relevant functions
False: Opposite of the above.
Note: Feedview functionality was present for only a short while prior to Firefox 1.5 Beta.
browser. feedview. timerInterval Integer Pref removed. Previously:
Determines how often to refresh the feed. Default value is 0 (no refresh).
Note: Feedview functionality was present for only a short while prior to Firefox 1.5 Beta.
browser. feedview. externalCSS String Pref removed. Previously:
Path to a custom CSS file to apply to feeds. Default value is an empty string.
Note: Feedview functionality was present for only a short while prior to Firefox 1.5 Beta.
browser. fixup. alternate. enabled Boolean True (default): Try to fix up http://foo to http://(prefix)foo(suffix)
False: Do not second-guess the user
browser. fixup. alternate. prefix String The prefix to prepend when attempting to fix an entered URL. Default is "www." (includes full stop). Requires browser.fixup.alternate.enabled be true.
browser. fixup. alternate. suffix String The suffix to append when attempting to fix an entered URL. Default is ".com". Requires browser.fixup.alternate.enabled be true.
browser. fixup. hide_user_pass Boolean True (default): When attempting to fix an entered URL, do not fix an entered password along with it (i.e. do not turn http://user:password@foo into http://user:password@(prefix)foo(suffix) but instead http://user@(prefix)foo(suffix))
False: Include entered password in fixed URL
browser. formfill. enable Boolean True (default): Save information entered in web page forms and the Search Bar
False: Opposite of the above
Note: In Firefox, this can be changed via "Tools → Options → Privacy → Saved Form Information → Save information I enter in web page forms and the Search Bar"
browser. forms. submit. backwards_compatible Boolean True (default): Leave off mandatory Content-Transfer-Encoding header when submitting HTML forms
False: Send header as the spec requires
Note: Sending the header "used to cause Bad Things, including server crashes" according to comments in the Mozilla source (see bug 83065). Eventually this pref may disappear.
browser. frames. enabled Boolean True (default): Enables the display of HTML frames
False: Opposite of the above; displays <noframes> content instead
browser. goBrowsing. enabled Boolean True (default): If a normal DNS lookup times out, try hitting Google
False: Opposite of the above
Note: No longer used
browser. helperApps. alwaysAsk. force Boolean True: Always ask what to do with an unknown MIME type, and disable option to remember what to open it with
False (default): Opposite of above
browser. helperApps. neverAsk. openFile String A comma-separated list of MIME types to open directly without asking for confirmation. Default value is an empty string.
browser. helperApps. neverAsk. saveToDisk String A comma-separated list of MIME types to save to disk without asking what to use to open the file. Default value is an empty string.
browser. hiddenWindowChromeURL String The chrome:// URL for the hidden window. Used in Mac OS X for when the browser is running but has no windows open. Default value is chrome://browser/content/hiddenWindow.xul
browser. history. grouping String How to group entries in the history window (not applicable for Firefox's History sidebar). Default value is day.
browser. history_expire_days Integer Number of days to remember visited pages in history. Default value is 9.
Note: In Firefox, this can be changed via "Tools → Options → Privacy → History → Remember visited pages for the last ___ days"
browser. jsannoyances. disabled Boolean The collective state of several other preferences; namely, dom.event.contextmenu.enabled, dom.disable_window_move_resize, dom.disable_window_flip, dom.disable_window_open_feature.status, and dom.disable_window_status_change. Used by the preferences dialog for tracking; changing the value of this preference manually does not change the tracked preferences.
True: Consider all of the above preferences to be true (except dom.event.contextmenu.enabled, which is considered to be false)
False (default): Opposite of the above
Note: Firefox 1.5 and above only.
browser. link. open_external Integer Where to open links sent to the browser from an external application
2: Opens external links in a new window
3: Opens external links in a new tab
1 (or anything else) (default): Opens external links in current window
Note: In Firefox, this can be changed via "Tools → Options → Advanced → Tabbed Browsing → Open links from other applications in:"
browser. link. open_newwindow Integer Where to open links that would normally open in a new window
2 (default): In a new window
3: In a new tab
1 (or anything else): In the current window
browser. link. open_newwindow. restriction Integer Firefox only. Source: The Burning Edge.
0 (default): Force all new windows opened by JavaScript into tabs.
1: Let all windows opened by JavaScript open in new windows. (Default behavior in IE.)
2: Catch new windows opened by JavaScript that do not have specific values set (how large the window should be, whether it should have a status bar, etc.) This is useful because some popups are legitimate — it really is useful to be able to see both the popup and the original window at the same time. However, most advertising popups also open in new windows with values set, so beware.
browser. link. open_newwindow. ui Integer Determine which new window open options are available from the UI. No longer used in Firefox 1.0. Default value is 3.
browser. offline Boolean Status of the "Work Offline" option
True: Attempt to retrieve pages from cache. Do not make external connections to retrieve resources.
False (default): Assume a connection is present and retrieve resources where necessary.
Note: In Firefox, this can be changed via "File → Work Offline"
browser. popups. showPopupBlocker Boolean True (default): Show an icon in the status bar when a popup has been blocked.
False: Do not show an icon in the status bar when a popup has been blocked.
browser. preferences. advanced. selectedTabIndex Integer Determines which tab in the Advanced section of the preferences is visible.
0 (default): General
1: Update
2: Security
browser. preferences. animateFadeIn Boolean True (default in Mac OS X): When switching prefs panels, change the height of the window and fade the new panel in over about a second.
False (default everywhere else): Do not animate switching pref panels
Note: Firefox 1.5 and above only.
browser. preferences. instantApply Boolean True (default in all platforms but Windows): Changes to preferences are active immediately. The preferences window is not modal. Instead of "OK" and "Cancel" buttons, there is only a "Close" button.
False: Changes to preferences occur after clicking "OK" button. The preference window is modal.
Note: Firefox 1.5 and above only.
browser. preferences. lastpanel Integer Which part of the preferences window was displayed the last time it was closed. In Firefox:
0: General
1: Privacy
2: Web Features
3: Downloads
4: Advanced
Note: In Firefox, this is determined by the section of "Tools → Options" you are viewing when you close the dialog.
browser. preferences. privacy. selectedTabIndex Integer Determines which tab in the Privacy section of the preferences is visible.
0 (default): History
1: Saved Forms
2: Passwords
3: Download History
4: Cookies
5: Cache
browser. related. autoload Integer Automatically load "What's Related" for a given URL
0: Always
1 (default): After first use (default)
2: Never
Note: This is not used in Firefox (there is no "What's Related").
browser. related. disabledForDomains String A comma-separated list of domains for which "What's Related" is disabled. Default value is an empty string.
Note: This is not used in Firefox (there is no "What's Related").
browser. related. enabled Boolean Setting for "What's Related"
True (default): Enable
False: Disable
Note: This is not used in Firefox (there is no "What's Related").
browser. related. provider String The URL to retrieve "What's Related" data from. Default value is http://www-rl.netscape.com/wtgn?
Note: This is not used in Firefox (there is no "What's Related").
browser. search. basic. min_ver String Version number used to determine which search engine plugins should be installed/displayed. Default value is 0.0.
browser. search. defaultenginename String Default search engine plugin to use. Default value is Google.
browser. search. defaulturl String URL to prepend to search terms. Default value is http://www.google.com/search?lr=&ie=UTF-8&oe=UTF-8&q=
browser. search. openintab Boolean True: When performing a search from the Search Bar, open the results in a new tab.
False (default): Open search results in the current tab/window.
Note: Firefox nightly trunk builds only.
browser. search. order. (digit) String (digit) is used to weight the search engine specified by the value for sorting in the list of search engines.
browser. search. order. (name) (. digit) String Used for weighting search engine entry sorting. Points to .properties file.
browser. search. param. (name). (digit). ("custom" or "default") String Used for adding arbitrary variables to the search query of the (name) search plugin.
browser. search. selectedEngine String Name of currently selected search engine plugin
browser. search. selectedEngineInDialog String Name of currently selected search engine plugin in the search dialog (used when the Search Bar is hidden)
Note: Firefox 1.5 and above only.
browser. search. update Boolean True (default): Automatically check for updates to search plugins.
False: Opposite of the above.
Note: Firefox 1.5 and above only.
browser. sessionhistory. cache_subframes Boolean True: Cache the content viewer (when browser.sessionhistory.max_viewers is greater than 0) for subframes
False (default): Opposite of the above
Note: Firefox 1.5 and above only.
browser. sessionhistory. max_entries Integer The maximum number of pages in the browser's session history, i.e. the maximum number of URLs you can traverse purely through the Back/Forward buttons. Default value is 50.
browser. sessionhistory. max_viewers Integer The number of content viewers to cache for "bfcache" (fast back/forward navigation). Default value is 3.
Note: Firefox 1.5 and above only.
browser. shell. checkDefaultBrowser Boolean Check the OS' default browser on startup.
True (default): Check to see if the browser is set as default; if not, ask if the user wants it set that way
False: Do not perform the check
Note: In Firefox, this can be changed via "Tools → Options → General → Default Browser"
browser. startup. homepage String URL of homepage, or pipe (|)-separated list of URLs to open in tabs when going to the homepage
Note: In Firefox, this can be changed via "Tools → Options → General → Homepage"
browser. startup. homepage_override. 1 Boolean Stub for browser.startup.homepage_override (used in Netscape 4.x). No longer used. Default value is false.
browser. startup. homepage_override. mstone String The last browser version (milestone) this profile was loaded with. If it differs from the current version, pref is changed to current version.
browser. startup. homepage_reset String If, during installation, the user requested that their homepage be reset, get the new homepage value from this location. Default value is resource:/browserconfig.properties
browser. startup. page Integer Page to open on browser startup
0: Blank
1 (default): Home (a.k.a. browser.startup.homepage)
2: Last (probably does not work)
browser. tabs. autoHide Boolean Behavior for the tab bar when only one tab exists
True (default): Hide the tab bar
False: Always show the tab bar
Note: In Firefox, this can be changed via "Tools → Options → Advanced → Tabbed Browsing → Hide the tab bar when only one web site is open"
browser. tabs. forceHide Boolean Display of the tab bar
True: Hide the tab bar
False: Show tab bar normally
Note: This is not used to enable/disable the tab bar. It's used internally to decide whether or not to show the tabbed bar.
browser. tabs. loadBookmarksInBackground Boolean True: When you open a bookmark in a new tab then that tab will load in the background without taking focus from the current tab.
False (default): When you open a bookmark in a new tab then that tab will become the current tab.
Note: In Firefox, this can be changed via "Tools → Options → Advanced → Tabbed Browsing → Select New Tabs from Bookmarks or History"
browser. tabs. loadDivertedInBackground Boolean Determines behavior of pages normally meant to open in a new window (target="_new" or from an external program), but that have instead been loaded in a new tab.
True: Load the new tab in the background, leaving focus on the current tab
False (default): Load the new tab in the foreground, taking the focus from the current tab.
Note: Setting this preference to True will still bring the browser to the front when opening links from outside the browser.
browser. tabs. loadFolderAndReplace Boolean True (default): When opening a folder of bookmarks in tabs, the existing tabs will be replaced by the new bookmark pages.
False: Existing tabs will be preserved when loading a folder of bookmarks. The bookmark pages will be loaded in tabs that are appended to the current tabs.
browser. tabs. loadGroup Integer 0: Append group to current tab set
1 (default): Replace current tab set with group
Note: This appears to be deprecated in favor of browser.tabs.loadFolderAndReplace
browser. tabs. loadInBackground Boolean Focus behavior for new tabs
True (default): Do not focus new tabs opened from links (load in background)
False: Opposite of above
Note: In Firefox, this can be changed via "Tools → Options → Advanced → Tabbed Browsing → Select new tabs opened from links"
browser. tabs. loadOnNewTab Integer Determines what will be displayed in a new tab
-1: Browser startup page
0 (default): Blank page
1: Homepage
2: Last visited page
Note: Does not work in Firefox 1.0 (see bug 269664).
browser. tabs. opentabfor. bookmarks Boolean Controls if a clicked bookmark will open in a new tab when middleclicked.
Note: Pref removed (obsolete). Functionality proposed as enhancement request.
browser. tabs. opentabfor. middleclick Boolean Determines the behavior of a link when middle-clicked.
True (default): Opens link in new tab
False: Opens link in new window
browser. tabs. opentabfor. searchdialog Boolean Determines whether to create a new tab for the search results from queries entered in the search dialog (used when the Search Bar is hidden)
Note: Firefox 1.5 and above only.
browser. tabs. opentabfor. urlbar Boolean Determines the behavior of pressing Enter in the address bar or clicking the Go button. Does not currently work.
True (default): Open URL in new tab
False: Open URL in current tab
Note: Functionality proposed as enhancement request.
browser. tabs. opentabfor. windowopen Boolean Pref removed (obsolete).
browser. tabs. showSingleWindowModePrefs Boolean Determines whether to display "Single Window Mode" settings in preferences (see bug 266759).
True: Show "Force links that open in new windows to open in..." options under "Tools → Options → Advanced → Tabbed Browsing"
False (default): Opposite of above
browser. tabs. warnOnClose Boolean True (default): The browser will prompt for confirmation when closing the browser when more than one tab is open.
False: No warnings will be given when closing the browser with more thanone tab.
Note: In Firefox, this can be changed via "Tools → Options → Advanced → Tabbed Browsing → Warn when closing multiple tabs"
browser. tabs. warnOnCloseOther Boolean True (default): The browser will prompt for confirmation when closing all other tabs from the tab context menu ("Close Other Tabs")
False: Opposite of the above
browser. throbber. url String Indicates what URL to load when the throbber is clicked. Default value is http://www.mozilla.org/products/firefox/central.html
browser. trim_user_and_password Boolean Seemingly nothing. (Never referenced in code.)
browser. triple_click_selects_paragraph Boolean True (default): Select the entire paragraph under the mouse cursor when triple-clicking.
False: Select the line under the mouse cursor when triple-clicking
Note: Firefox 1.5 and above only.
browser. turbo. enabled Boolean Pref removed (obsolete). Previously:
Determined whether to load browser in "Turbo Mode" (aka "quick launch") (Windows/Mozilla Suite only)
True: Load some Mozilla code into memory on Windows boot
False (default): Load browser normally on program execution
browser. underline_anchors Boolean Determines default text-decoration of anchor elements.
True (default): Underlines links
False: Opposite of above
Note: In Firefox, this can be changed via "Tools → Options → General → Fonts & Colors → Underline links"
browser. update. resetHomepage Boolean Determine whether to reset homepage during browser installation
True: Reset homepage in browser.startup.homepage to value in browser.startup.homepage_reset
False (default): Do not reset homepage
browser. urlbar. autoFill Boolean True: Enables inline autocomplete.
False (default): Opposite of above.
browser. urlbar. clickSelectsAll Boolean True (default in non-Unix builds): Select the contents of the address bar when it is clicked
False (default everywhere else): Opposite of above
browser. urlbar. matchOnlyTyped Boolean Determines behavior of autocomplete in Location Bar
True: Only matches typing against URLs specifically typed into Location Bar
False (default): Match against history
browser. visited_color String The default color for visited links as a hex code. Default is #551A8B
Note: In Firefox, this can be changed via "Tools → Options → General → Fonts & Colors → Visited Links"
browser. windows. loadOnNewWindow Integer Set what should be displayed in a newly created window
-1: Browser Startup Page
0: Blank Page
1 (default): Your Homepage
2: Last Visited
browser. xul. error_pages. enabled Boolean True (default in Firefox 1.5 and above): The browser will use error pages.
False (default in Firefox 1.0.x and below): The browser will use error alert boxes.

Config.*

Name Type Meaning of Values
config. trim_on_minimize Boolean Windows-only. Determines how Windows handles memory for the browser when minimizing. Setting to False will often prevent delays when restoring the window (see bug 76831).
True (default): Allow Windows to trim the working set when the browser is minimized
False: Prevent Windows from trimming the working set
config. use_system_prefs Boolean True: Use preferences set by operating system (e.g. proxies, accessibility)
False (default): Opposite of the above
Note: Seems to be unused in Firefox 1.0
config. use_system_prefs. accessibility Boolean True: The system is configured with accessibility features; use them
False (default): Opposite of the above
Note: Seems to be unused in Firefox 1.0

Content.*

Name Type Meaning of Values
content. interrupt. parsing Boolean True (default): Enable interruption of parsing to return to the application's event loop from time to time
False: Opposite of the above
content. max. tokenizing. time Integer Determines time in microseconds after which parsing is interrupted to return to the application's event loop. Default value is 3×content.notify.interval. Synchronize as a multiple of content.notify.interval for best results.
content. maxtextrun Integer Determines (in part) when to display a new portion of text to the layout from the buffer (the maximum number of text runs that may fly by before doing a notification). Value is in kilobytes. Default value is 8191. For more information, see bug 77540.
content. notify. backoffcount Integer Determines the number of initial reflows during timer-based rendering. After this number of reflows, the page is only reflowed when the calculation of the layout of larger parts of the page is finalized. Default value is -1 (never).
content. notify. interval Integer Determines time steps for the initial reflows defined by content.notify.backoffcount in microseconds. Default value is 120000. Values below 100000 are not recommended. Synchronize with nglayout.initialpaint.delay for best performance.
content. notify. ontimer Boolean True (default): Enable timer-based reflows during page rendering
False: Opposite of the above
content. switch. threshold Integer Determines how long to wait for user input (mouse movement or typing) in microseconds until switching to low frequency interrupt mode. (High frequency interrupt mode provides better UI responsiveness at the expense of load time.) Default value is 750000.

DOM.*

Name Type Meaning of Values
dom. allow_scripts_to_close_windows Boolean Determines which close() operations are legal.
True: Any script may close any window
False (default): Only windows opened via script may be closed via close().
dom. disable_image_src_set Boolean Determines whether scripts may change the .src member of image objects (effectively, whether images can be changed via JavaScript)
True: Scripts may not modify .src of images
False (default): Opposite fo above
Note: In Firefox, this can be changed via "Tools → Options → Web Features → Enable JavaScript / Advanced → Allow scripts to change images"
dom. disable_open_click_delay Integer If a popup will be created as the result of a setTimeout() or setInterval() JavaScript call and the delay specified is smaller than this value (in milliseconds), handle the popup according to the current popup blocker settings. Default value is 1000.
dom. disable_open_during_load Boolean Determines popup blocker behavior
True (default): Block popup windows created while the page is loading
False: Allow popup windows
Note: In Firefox, this can be changed via "Tools → Options → Web Features → Block Popup Windows"
dom. disable_window_flip Boolean Determines whether windows can be focus()ed via non-chrome JavaScript.
True: Windows may not be set as active via JavaScript
False (default): Opposite of the above
Note: In Firefox, this can be changed via "Tools → Options → Web Features → Enable JavaScript / Advanced → Allow scripts to raise or lower windows"
dom. disable_window_move_resize Boolean Determines whether windows can be moved or resized via non-chrome JavaScript.
True: Windows may not be moved or resized via JavaScript
False (default): Opposite of the above
Note: In Firefox, this can be changed via "Tools → Options → Web Features → Enable JavaScript / Advanced → Allow scripts to move or resize existing windows"
dom. disable_window_open_feature. * Boolean Web Page authors can disable many features of a popup window that they open. Setting these preferences to true will override the author's settings and ensure that that feature is enabled and present in any popup window.
close: Prevents the close button from being disabled.
directories: Prevents the bookmarks toolbar from being hidden.
location: Prevents the address bar from being hidden
menubar: Prevents the menubar from being hidden.
minimizable: Prevents popup window minimization from being disabled.
personalbar: Prevents the bookmarks toolbar from being hidden.
resizable: Prevents popup window resizing from being disabled.
scrollbars: Prevents the scrollbars on a popup from being disabled.
status: Prevents the status bar from being hidden.
titlebar: Prevents the title bar from being hidden.
toolbar: Prevents the navigation toolbar from being hidden.
dom. disable_window_status_change Boolean Determines whether the text in the browser status bar may be set by non-chrome JavaScript.
True (default): JavaScript access to window.status is disabled
False: Opposite of the above
Note: In Firefox, this can be changed via "Tools → Options → Web Features → Enable JavaScript / Advanced → Allow scripts to change status bar text"
dom. event. contextmenu. enabled Boolean Determines whether the oncontextmenu event can be caught by non-chrome JavaScript (e.g., in an anti-right-click script).
True (default): the opposite of below.
False: Webpages will not be able to affect the context menu event, thus allowing to access the context menu all the time.
Note: In Firefox, this can be changed via "Tools → Options → Web Features → Advanced → Allow scripts to disable or replace context menus"
dom. max_script_run_time Integer Determines the maximum amount of time in seconds a script can run. Default value is 5. Negative values are ignored and 5 seconds is used instead.
Note: Requires a browser restart.
dom. popup_allowed_events String A space-separated list of the events that are allowed to create popups. Default value is "change click dblclick mouseup reset submit". A presumably complete list of events from mozilla/content/events/src/nsDOMEvent.cpp:
Form events:
select:
change:
input:
submit:
reset:

Other events:

keydown:
keypress:
keyup:
mousedown:
mouseup:
click:
dblclick:
error:
dom. popup_maximum Integer The maximum number of simultaneously open popup windows. Default value is 20.

Editor.*

These settings affect libeditor (i.e. Composer and Mail). Most have no effect in Firefox.

Name Type Meaning of Values
editor. css. default_length_unit String Determines the default units for CSS rules.
cm: centimeters
em: ems (width of the capital letter "M")
ex: ex (height of the lower-case "x")
in: inches
mm: milimeters
%: percentage of parent element
pc: picas (1/6th of an inch)
px (default): pixels
pt: points (1/72nd of an inch)
editor. htmlWrapColumn Integer The column at which HTML source wraps. Default value is 72.
editor. positioning. offset Integer The default offset, both X and Y, of absolutely positioned elements. Default value is 0.
editor. quotesPreformatted Boolean Originally meant to be a temporary preference to control the behavior of plaintext quotations inserted into email.
True: Wrap quoted email text in a pre element
False (default): Wrap quoted email text in a span element
editor. resizing. preserve_ratio Boolean Determines the behavior of resizing images in Composer.
True (default): Preserve ratio of image while resizing
False: Allow free resizing of height and width
editor. singleLine. pasteNewlines Integer Determines the behavior when pasting content containing newlines into single-line text boxes.
0 (default in Linux): Paste content intact (include newlines)
1 (default everywhere else): Paste the content only up to (but not including) the first newline
2: Replace each newline with a space
3: Remove all newlines from content
4: Substitute commas for newlines in text box
editor. use_css Boolean Determines the preferred method of formatting content.
True (default): Use CSS styling where appropriate
False: Use non-CSS methods of styling content
editor. use_custom_colors Boolean Determines whether to use user-specified colors for content.
True: Use colors specified in editor.* preferences for content
False (default): Use the default colors

Extensions.*

This branch of preferences is usually used to hold settings for installed extensions, but there are a few that deal with extensions and themes in general.

Name Type Meaning of Values
extensions. {GUID}. description String Specify a custom description for the extension whose GUID is specified (see Localize extension descriptions for application).
extensions. disabledObsolete Boolean Indicates whether obsolete extensions have been disabled as a result of a change in the browser version.
extensions. dss. enabled Boolean True: Enable dynamic skin (theme) switching.
False (default): Require a browser restart when switching themes.
Note: Switching themes dynamically is buggy (see bug 226791).
extensions. dss. switchPending Boolean True: Non-dynamic theme switch pending a browser restart
False (default): Opposite of the above
extensions. getMoreExtensionsURL String Determines the URL used for the "Get More Extensions" link in "Tools → Extensions" dialog.
extensions. getMoreThemesURL String Determines the URL used for the "Get More Themes" link in "Tools → Themes" dialog.
extensions. ignoreMTimeChanges Boolean True: Prevent extensions system from using last-modified file metadata when determining whether an extension is new (and should therefore be registered)
False (default): Opposite of the above
Note: Nightlies only.
extensions. lastAppVersion String The last version of the browser to successfully load extensions. Used to determine whether or not to disable extensions due to possible incompatibilities.
extensions. logging. enabled Boolean True: Enables some extra extension system logging (can reduce performance)
False (default): Opposite of the above
Note: Nightlies only
extensions. reporter. hidePrivacyStatement Boolean True: The user has viewed and agreed to the privacy statement for the Report Broken Website tool, so don't show it again.
False: Display the privacy statement when opening the Report Broken Website tool.
extensions. update. autoUpdate Boolean True: Automatically download and install available updates
False (default): Opposite of the above
Note: Not implemented
extensions. update. autoUpdateEnabled Boolean True (default): Allow automatic checking for updates at the specified interval
False: Opposite of the above
extensions. update. count Integer The number of extension/theme/etc. updates available. Default value is 0.
extensions. update. enabled Boolean True (default): Allow checking for updates
False: Opposite of the above
Can be overridden on a per-extension basis by setting extensions.{GUID}.update.enabled.
extensions. update. interval Integer Determines how often to check the update URL for updates. Can be overridden on a per-extension basis by setting extensions.{GUID}.update.interval.
In Firefox 1.0.x and below, default value is 604800000 (milliseconds in 1 week).
In Firefox 1.5 and above, default value is 86400 (seconds in 1 day).
extensions. update. lastUpdateDate Integer When the last extension update occurred, in UNIX epoch format (seconds since 1970-01-01). Default value is 0.
extensions. update. severity. threshold Integer The number of pending Extension/Theme updates you can have before the update notifier goes from low to medium severity. Default value is 5.
extensions. update. url String Determines the URL queried when polling for extension updates. Can be overridden on a per-extension basis by setting extensions.{GUID}.update.url. Default value is pulled from chrome://mozapps/locale/update/update.properties.

Font.*

The majority of the font.* entries are of the form:

font.(font property).(font type).(language code)

The (font property) indicates that the value of the entry is one of the following:

name-list 
A comma-and-space-delimited list of font names corresponding to the (font type) and (language code) (String)
name 
A font name (String)
size 
The font size, in pixels (Integer)

The (font type) indicates which CSS generic-family is being referenced in the value, or simply whether the font is fixed-width or variable-width. The (font type) is one of the following:

serif 
(e.g. Times)
sans-serif 
(e.g. Helvetica)
cursive 
(e.g. Zapf-Chancery)
fantasy 
(e.g. Western)
monospace 
(e.g. Courier)
fixed 
Any fixed-width font
variable 
Any variable-width font

The (language code) is an ISO 639-2 value.

Other font.* entries are listed below.

Name Type Meaning of Values
font. default (. language code) String The default generic-family to use. If a language code is specified, the preference only applies to that language.
serif (default): Serif
sans-serif: Sans-serif
font. language. group String The user's language group. Pulled from the localized data at chrome://global/locale/intl.properties by default on installation.
font. size. nav4rounding Boolean Unused (obsolete). Previously:
True: In Windows, adjust rounding of some pixel font sizes to match Netscape 4.x's (incorrect) rounding
False (default): Display fonts normally

General.*

Name Type Meaning of Values
general. autoScroll Boolean Status of the autoscroll option (middle-clicking on a web page produces a scrolling icon and will automatically scroll the page based on the pointer's relative location to the icon)
True (default): Activate autoscroll
False: Opposite of the above
Note: In Firefox, this can be changed via "Tools → Options → Advanced → Browsing → Use autoscrolling"
general. config. filename String A .cfg file to parse and read for AutoConfig. Unset by default.
general. config. obscure_value Integer An integer to use when obscuring the AutoConfig file saved to and read from disk. Default value is 13 (effectively, ROT-13 the content).
general. config. vendor String A vendor ID associated with the AutoConfig file.
general. skins. selectedSkin String The current skin used by the browser. Default value is classic/1.0.
Note: In Firefox, this can be changed via "Tools → Themes"
general. smoothScroll Boolean Status of ths smooth scrolling option (scrolling on a web page moves page content pixelwise rather than line-by-line)
True: Activate smooth scrolling
False (default): Opposite of the above
Note: In Firefox, this can be changed via "Tools → Options → Advanced → Browsing → Use smooth scrolling"
general. startup. browser Boolean True (default): When launching Mozilla, load the browser component
False: Opposite of the above
Note: This preference has little to no significance in Firefox, as it is only a browser.
general. useragent. contentlocale String The content locale ISO 639-2 value specified in the User-Agent string
general. useragent. extra. (product name/version) String Allows an arbitrary number of strings to be added to the end of the User-Agent string. By default, general.useragent.extra.firefox is defined and set to Firefox/(version). See bug 274928 for more information.
Note: Firefox 1.5 and above only.
general. useragent. locale String ISO 639-2 value representing the user's language for the User-Agent string
general. useragent. override String A complete User-Agent string to use in place of the default.
general. useragent. security String Security level of the browser in the User-Agent string
N: No security
U (default): Strong security
I: Weak security
general. useragent. vendor String Vendor in the User-Agent string. Default value depends on browser (Firefox in Firefox 1.0).
Note: No longer specified by default in Firefox 1.5.
general. useragent. vendorSub String Vendor substring in the User-Agent string. Default value depends on browser version (1.0 in Firefox 1.0)
Note: No longer specified by default in Firefox 1.5.

Intl.*

Name Type Meaning of Values
intl. accept_charsets String Character sets in which to accept data. Default value is iso-8859-1,*,utf-8.
intl. accept_languages String ISO 639-2 values of languages to accept. Default value is determined by localized information in chrome://navigator/locale/navigator.properties.
intl. charset. default String Determines the default character set. Default value is chrome://global-platform/locale/intl.properties
intl. charset. detector String Determines which locale URI sets how character set are detected in the browser
intl. charsetmenu. browser. cache String A comma-and-space-delimited list of cached character sets for the browser
intl. charsetmenu. browser. cache. size Integer Number of character sets to cache. Default value is 5.
intl. charsetmenu. browser. more* String A comma-and-space-delimited list of character sets to display in the character encoding menu
Note: In Firefox, these menus are viewable via "View → Character Encoding → More Encodings"
intl. charsetmenu. browser. static String A comma-and-space-delimited list of character sets to always display in the character encoding menu.
Note: In Firefox, this can be changed via "View → Character Encoding → Customize List"
intl. charsetmenu. browser. unicode String A comma-and-space-delimited list of Unicode character sets to display in the character encoding menu
Note: In Firefox, this menus is viewable via "View → Character Encoding → More Encodings → Unicode"
intl. charsetmenu. composer. cache String A comma-and-space-delimited list of cached character sets for Composer
intl. charsetmenu. mailedit String Determines the layout of the Character Coding menu in Mozilla Mail/News (message editor)
intl. charsetmenu. mailview. cache String A comma-and-space-delimited list of cached character sets for Mozilla Mail/News (main view)
intl. collationOption String A workaround to get correct column sorting in Mozilla Mail in Japanese builds of Linux. Default value is an empty string. Setting it to useCodePointOrder enables the workaround (see bug 18338).
intl. content. langcode String Default content language code
intl. fallbackCharsetList. (character set) String Determines the substitute character set if (character set) is unavailable.
intl. jis0208. map String Determines the map to use for JIS X 0208
CP932 (default in Windows): Use a CP932-compatible map
IBM943 (default in OS/2): Use an IBM943-compatible map
intl. keyboard. per_window_layout Boolean True: Allow different windows to retain their own keyboard locale settings (see bug 186549)
False (default): Opposite of the above
intl. locale. matchOS Boolean Determines how to decide locale
True: Use the locale the OS is using
False (default): Opposite of the above
intl. menuitems. alwaysappendaccesskeys String Specifies URI to determine if access keys are appended to menu items
intl. menuitems. insertseparatorbeforeaccesskeys String Specifies URI to determine if there is a space before the paranthesis of the accesskey in the menu's label (see bug 298712).

JavaScript.*

Name Type Meaning of Values
javascript. allow. mailnews Boolean Determines whether JavaScript can be executed in Mozilla Mail/News.
True: Enable JavaScript
False (default): Disable JavaScript
javascript. enabled Boolean Determines whether JavaScript can be executed in the browser.
True (default): Enable JavaScript
False: Disable JavaScript
Note: In Firefox, this can be changed via "Tools → Options → Web Features → Enable JavaScript"
javascript. options. showInConsole Boolean Determines whether chrome errors should be displayed in the JavaScript Console.
True: Show chrome errors in the console
False (default): hide errors
javascript. options. strict Boolean Determines whether to enable strict JavaScript warnings in the JavaScript Console.
True: Enable strict JavaScript error reporting
False (default): Opposite of the above

Layout.*

Name Type Meaning of Values
layout. enable_japanese_specific_transform Boolean Determines whether or not to replace backslashes with Yen signs in documents encoded in one of Japanese legacy encodings (EUC-JP, Shift_JIS, ISO-2022-JP)
True: Replace backslashes
False (default): Opposite of the above
layout. frames. force_resizability Boolean Determines whether frame noresize attribute is honored.
True: All frames will be resizable, resulting in a movable separator between frames.
False (default): The resizability of frames is determined by the web page.
layout. reflow. async. duringDocLoad Boolean True: Use asynchronous reflows
False (default): Opposite of the above
layout. reflow. timeslice Integer Upper bound on time spent reflowing (in microseconds). Default value is 1000000 (1 second).
layout. word_select. eat_space_to_next_word Boolean Determines whitespace selection behavior when double-clicking a word
True (default): Select the space up to but not including the next word along with the word
False: Just select the word with no extra whitespace
layout. word_select. stop_at_punctuation Booelan Determines punctuation selection behavior when double-clicking a word
True (default): Don't select punctuation automatically with the word
False: Select the punctuation as well as the word
layout. xml. prettyprint Boolean Determines how to output unstyled XML data in the browser
True (default): Run the XML through the "pretty print" XSLT at chrome://communicator/content/xml/XMLPrettyPrint.xsl
False: Attempt to parse it in-browser or download, depending on the MIME type sent

Middlemouse.*

Name Type Meaning of Values
middlemouse. contentLoadURL Boolean Determines how to handle middle-clicks in the content area.
True (default in Linux): Go to whatever address is currently in the clipboard
False (default in all but Linux): Handle middle-clicks normally.
middlemouse. openNewWindow Boolean Determines behavior of middlemouse.contentLoadURL when that preference is true.
True (default): Open links that are middle-clicked in a new window
False: Opposite of the above.
middlemouse. paste Boolean Determines behavior of middle-clicks when text fields or text areas have focus.
True (default in Linux): Middle-clicking a text field or area will paste whatever is in your clipboard into the text field or area.
False (default in all but Linux): Opposite of the above
middlemouse. scrollbarPosition Boolean Determines behavior of middle-clicks in the scrollbar.
True (default in Linux): Center the scroll position on the scrollbar at the coordinates of the middle-click
False (default in all but Linux): Don't move the scroll position on middle-click

Mousewheel.*

These fall into two groups, vertical and horizontal scroll. The general form is:

  • mousewheel.(modifier key).(type)
  • mousewheel.horizscroll.(modifier key).(type)

Type is then one of:

action 
integer value that determines the type of action:
  • 0 - Scroll document by a number of lines (given by the numlines property)
  • 1 - Scroll document by one page
  • 2 - Move back/forward in history
  • 3 - Make text larger/smaller
numlines 
number of lines to scroll by (if relevant)
sysnumlines 
use system preferences to determine how many lines to scroll by

Network.*

Name Type Meaning of Values
network. auth. use-sspi Boolean True (default in Windows): Use SSPI instead of GSSAPI for Kerberos-based authentication
False: Opposite of the above
Note: Firefox 1.5 and above only.
network. autodial-helper. enabled Boolean Help Windows NT, 2000, and XP dialup a RAS connection when a network address is unreachable.
True: Launch dialer when address is unreachable
False (default): Display error message
network. automatic-ntlm-auth. allow-proxies Boolean Enable automatic use of the operating system's NTLM implementation to silently authenticate the user with their Windows domain logon with proxy servers. (See Integrated Authentication for more information)
True (default): Automatically authenticate with proxy servers
False: Prompt for authentication
network. automatic-ntlm-auth. trusted-uris String A comma-and-space-delimited list of URIs with which to automatically authenticate via NTLM (Windows domain logon). Default value is an empty string. (See Integrated Authentication for more information)
network. cookie. alwaysAcceptSessionCookies Boolean Determines whether to accept session cookies (kept for the duration of the browser session, then removed) if network.cookie.lifetimePolicy is 1.
True: Accept session cookies without prompting
False (default): Prompt before accepting session cookies
network. cookie. blockFutureCookies Boolean True: Allow sites to set cookies unless the user has removed cookies set by the site
False (default): Removed cookies do not affect future cookie acceptance.
network. cookie. cookieBehavior Integer Determines how the browser should handle cookies.
0 (default): Enable all cookies
1: Allow cookies from originating server only
2: Disable all cookies
3: Use P3P policy to decide
Note: In Firefox, this can be changed via "Tools → Options → Privacy → Cookies → Allow sites to set cookies / for the originating web site only"
network. cookie. denyRemovedCookies Boolean Seemingly unused.
network. cookie. disableCookieForMailNews Boolean Determines how Mozilla Mail/News should handle cookies.
True (default): Reject all cookies in Mozilla Mail/News
False: Accept cookies normally
network. cookie. enableForCurrentSessionOnly Boolean True: Delete all cookies at the end of the browser session
False (default): Opposite of the above
Note: This setting is deprecated in favor of network.cookies.lifetimePolicy (setting that to 2 is the equivalent of this preference set to True)
network. cookie. lifetime. days Integer Determines the number of days to keep cookies if network.cookie.lifetimePolicy is 3. Default value is 90.
network. cookie. lifetimePolicy Integer Determines how browser sets cookie lifetimes.
0 (default): Use supplied lifetime
1: Ask before accepting
2: Accept for session only
3: Cookies last for the number of days specified in network.cookie.lifetime.days
Note: In Firefox, this can be changed via "Tools → Options → Privacy → Cookies → Keep Cookies"
network. cookie. maxNumber Integer Determines the maximum amount of cookies to be stored. Valid range is from 0-65535 (RFC 2109 and RFC 2965 require this to be at least 300). Default value is 1000.
network. cookie. maxPerHost Integer Determines the maximum amount of cookies to be stored per host. Valid range is from 0-65535 (RFC 2109 and RFC 2965 require this to be at least 20). Default value is 50.
network. cookie. p3p String Determines the browser's P3P handling. An 8-character string. Default value is ffffaaaa. Each position in the string may be one of the following:
f: Flag the cookie
d: Accept the cookie, but downgrade it to a session-only lifetime
a: Accept the cookie
r: Reject the cookie
The character positions are as follows:
1st position: First party cookies from sites with no policy
2nd position: Third party cookies from sites with no policy
3rd position: First party cookies from sites that collect personal information without permission
4th position: Third party cookies from sites that collect personal information without permission
5th position: First party cookies from sites that collect personal information only with permission
6th position: Third party cookies from sites that collect personal information only with permission
7th position: First party cookies from sites that don't collect personal information
8th position: Third party cookies from sites that don't collect personal information
Note: P3P functionality is not present in Firefox and will probably be removed from Mozilla Suite (see bug 225287).
network. cookie. p3plevel Integer Security level of filtering for cookies
0: Low (use afafaaaa)
1 (default): Medium (use ffffaaaa)
2: High (use frfradaa)
3: Custom (use value in network.cookies.p3p)
Note: P3P functionality is not present in Firefox and will probably be removed from Mozilla Suite (see bug 225287).
network. cookie. prefsMigrated Boolean Indicates whether some cookie preferences — previously stored in deprecated preferences — have been migrated to current preferences.
True: Consult current preferences for cookie prefs
False (default): Read deprecated preferences, update current preferences, then set this preference to true
network. dir. format Integer How to format directory listings (e.g., from FTP servers)
1: Raw — exactly what comes off the network
2 (default): HTML
3: application/http-index-format (requires code to parse/display that is not present by default in Firefox; it is present in the Mozilla application suite)
network. dns. disableIPv6 Boolean Determines whether to perform IPv6 name lookups (see bug 68796)
True (default in OS X): Do not perform lookups
False (default in all others): Opposite of the above
network. dns. ipv4OnlyDomains String A comma-separated list of domains for which DNS lookups are for IPv4 addresses only (see bug 68796). Default value is .doubleclick.net.
network. dnsCacheEntries Integer Determines the maximum number of entries to keep in the DNS cache. Default value is 20.
network. dnsCacheExpiration Integer Determines the maximum number of seconds to cache resolved DNS entries. Default value is 60.
network. enableIDN Boolean Determines whether to use IDN (International Domain Name) support in the browser
True (default): Enable IDN support
False: Opposite of the above
Note: In Firefox 1.0, this preference did not "stick" (see bug 261934). Fixed in 1.0.1.
network. enablePad Boolean Determines whether the browser is allowed to perform proxy autodiscovery
True: Autodiscovery enabled
False (default): Opposite of the above
network. ftp. anonymous_password String Password to use when connecting to anonymous FTP servers. Sent instead of "mozilla@example.com" if advanced.mailftp is true. Not set by default.
network. ftp. idleConnectionTimeout Integer Time in seconds until an idle FTP connection is dropped. Default value is 300.
network. hosts. nntp_server String Pref to be removed (obsolete). Previously: News server for Mozilla Mail/News. Default value is news.mozilla.org.
network. hosts. pop_server String POP (incoming mail) server for Mozilla Mail/News. Default value is mail.
network. hosts. smtp_server String SMTP (outgoing mail) server for Mozilla Mail/News. Default value is mail.
network. http. accept-encoding String Comma-separated list of encoding types to accept from server. Sent with HTTP requests in Accept-Encoding header. Default value is gzip, deflate.
Note: compress is not a supported encoding (see bug 196406).
network. http. accept. default String Comma-separated list of MIME types to accept from server. Sent with HTTP requests in Accept header. Default value is text/xml,application/xml,application/xhtml+xml,text/html; q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5. (The space is actually not present and was only inserted to make it wrap.)
network. http. connect. timeout Integer Pref removed (unused). Previously: determines how long to wait for a response until registering a timeout. Default value is 30.
network. http. default-socket-type String Determines the socket type to be used for normal HTTP traffic. Default value is an empty string, indicating a normal TCP/IP socket type. Seems to be unused.
network. http. keep-alive Boolean Determines whether to use HTTP Keep-Alive connections. If more than one request is made, the browser attempts to reuse open connections that have been kept alive.
True (default): Send Connection: keep-alive header and Keep-Alive header based on contents of network.http.keep-alive.timeout
False: Opposite of the above (recommended in case of problems)
Note: This preference is effectively obsolete, as all connections are considered keep-alive in HTTP/1.1.
network. http. keep-alive. timeout Integer Requested timeout for Keep-Alive connections in seconds. Default value is 300.
network. http. max-connections Integer Determines the maximum number of simultaneous HTTP connections. Default value is 24. Valid values are between 1 and 65535 inclusive.
network. http. max-connections-per-server Integer Determines the maximum number of simultaneous HTTP connections that can be established per host. If a proxy server is configured, then the server is the proxy server. Default value is 8. Valid values are between 1 and 255 inclusive.
network. http. max-persistent-connections-per-proxy Integer If network.http.keep-alive is true, and if a proxy server is configured, then a new connection will only be attempted if the number of active persistent connections to the server is less than this preference. Default value is 4. Valid values are between 1 and 255 inclusive.
network. http. max-persistent-connections-per-server Integer If network.http.keep-alive is true, and if a proxy server is not configured, then a new connection will only be attempted if the number of active persistent connections to the server is less than this preference. Default value is 2. Valid values are between 1 and 255 inclusive.
network. http. phishy-userpass-length Integer A number between 0 and 255. Warn the user if we load an URL containing a userpass field (e.g., http://user:pass@example.com/) unless its length is less than this threshold. Default value is 1.
network. http. pipelining Boolean Determines whether to use HTTP/1.1 pipelining.
True: Enable pipelining
False (default): Disable pipelining
Note: Pipelining is not well-supported by some servers and proxies. Things may break — use with caution.
network. http. pipelining. firstrequest Boolean Pref removed (unused)
network. http. pipelining. maxrequests Integer Determines the maximum number of HTTP requests in the pipeline (sent sequentially without waiting for a response). Values greater than 8 are assumed to be 8; values less than 1 are assumed to be 1. Default value is 4.
network. http. proxy. keep-alive Boolean Determines whether to use HTTP Keep-Alive connections when a proxy server is configured. If more than one request is made, the browser attempts to reuse open connections that have been kept alive.
True (default): Send Connection: keep-alive header and Keep-Alive header based on contents of network.http.keep-alive.timeout
False: Opposite of the above (recommended in case of problems)
Note: This preference is effectively obsolete, as all connections are considered keep-alive in HTTP/1.1.
network. http. proxy. pipelining Boolean Determines whether to use HTTP/1.1 pipelining when a proxy server is configured.
True: Enable pipelining
False (default): Disable pipelining
Note: Pipelining is not well-supported by some servers and proxies. Things may break — use with caution.
network. http. proxy. version String Determines which HTTP version to use when a proxy server is configured. Default value is 1.1, though 1.0 is recommended for some finnicky proxies (such as the Junkbuster proxy).
network. http. redirection-limit Integer Determines how many consecutive HTTP redirects the browser will follow. Default value is 20. Setting it to 0 will stop all redirects from occuring.
Note: These are header-based redirects, not (for example) <meta http-equiv="refresh"> HTML-based redirects.
network. http. request. max-start-delay Integer Determines amount of time (in seconds) to suspend pending requests, before spawning a new connection, once the limit on the number of persistent connections per host (network.http.max-persistent-connections-per-server) has been reached. However, a new connection will not be created if max-connections (network.http.max-connections) or max-connections-per-server (network.http.max-connections-per-server) has also been reached. Default value is 10.
network. http. request. timeout Integer Pref removed (unused). Previously: HTTP-specific network timeout. Default value is 120.
network. http. sendRefererHeader Integer Determines when to send the Referer HTTP header.
0: Never send the referring URL
1: Send only on clicked links
2 (default): Send for links and images
network. http. sendSecureXSiteReferrer Boolean Determines how to handle Referer HTTP header when navigating between secure (HTTPS) hosts.
True (default): Send referring URL normally (default for compatibility reasons, see bug 141641)
False: Send no referring URL
network. http. use-cache Boolean Determines whether to enable caching of HTTP documents. Appears to be unused.
True (default): Enable caching
False: Opposite of the above
network. http. version String Determines which HTTP version to use. Default value is 1.1.
network. IDN_show_punycode Boolean Determines how to display IDN hostnames in the Location Bar (see bug 282270).
True (default): All IDN (UTF-8) domain names will be normalized to punycode.
False: Display IDN domain names in UTF-8
Note: Addresses may be input as UTF-8 regardless of this setting.
network. IDN. blacklist_chars String If a domain name contains any of the characters in this preference's value, display the domain in punycode, overriding network.IDN_show_punycode and network.IDN.whitelist (see bug 301694). Default value is a string containing the Unicode characters U+2044 FRACTION SLASH and U+2215 DIVISION SLASH.
Note: Firefox 1.5 and above only.
network. IDN. whitelist. (TLD) Boolean When network.IDN_show_punycode is false, these preferences are checked against the top-level domain of any IDN domain name. If there is a whitelist entry for the top-level domain and the entry is set to true, then the IDN is shown as intended. Otherwise, it is shown in punycode. By default, the top-level domains ac, at, br, ch, cl, cn, de, dk, fi, gr, hu, info, io, jp, kr, li, lt, museum, no, se, sh, th, tm, and tw are whitelisted (set to true).
Note: Firefox 1.5 and above only.
network. image. imageBehavior Integer Determines when images should be loaded.
0 (default): Load all images
1: Load images from same (originating) server only
2: Do not load any images
Note: In Firefox, this can be changed via "Tools → Options → Web Features → Load Images / for the originating web site only"
In Firefox 1.5 and above, this preference has been renamed to permissions.default.image.
network. image. warnAboutImages Boolean Pref unused (feature disabled). Previously:
Determines whether to prompt the user before loading an image.
True: Load no images until user confirms
False (default): Load images normally
network. negotiate-auth. allow-proxies Boolean True (default): Allow SPNEGO by default when challenged by a proxy server. (See Integrated Authentication and bug 266485 for more information.)
False: Opposite of the above
network. negotiate-auth. delegation-uris String A comma-and-space-delimited list of sites for which the browser may delegate user authorization to the server. (See Integrated Authentication for more information.) Default value is an empty string.
network. negotiate-auth. gsslib String Path to a specific GSSAPI library. Allows the browser (e.g.) to load different Kerberos implementations at the user's request. Default value is an empty string.
Note: See bug 295109 for more information.
network. negotiate-auth. trusted-uris String A comma-and-space-delimited list of sites that are permitted to engage in SPNEGO authentication with the browser. (See Integrated Authentication for more information.) Default value is an empty string.
network. negotiate-auth. using-native-gsslib Boolean True (default): Use the GSS lib that comes standard with the host operating system
False: Use the GSSAPI library specified in network.negotiate-auth.gsslib.
network. ntlm. send-lm-response Boolean Determines whether or not the LM hash will be included in response to a NTLM challenge. Servers should almost never need the LM hash, and the LM hash is what makes NTLM authentication less secure.
True: Send the LM hash
False (default): Opposite of the above
Note: Does not affect network.automatic-ntlm-auth.* settings. See bug 250961 for more information.
network. online Boolean Indicates whether the user is currently online. Used for enabling/disabling various options in the UI.
True (default): User is online
False: Opposite of the above
network. prefetch-next Boolean Determines whether to use link prefetching.
True (default): Silently prefetch hinted documents and store in the cache
False: Disable all link prefetching
network. protocol-handler. expose-all Boolean Determines whether to expose (enable) all protocol handlers. This preference overrides more specific preferences, e.g. network.protocol-handler.expose.mailto.
True: Try to open link clicks in browser first, then fail over to system handlers
False: Do not expose all protocol handlers
network. protocol-handler. expose. (protocol) Boolean Determines whether to expose (enable) the specified protocol handler. These preferences are overridden by network.protocol-handler.expose-all.
True: Try to open link clicks in browser firsst, then fail over to system handlers
False: Do not expose this protocol handler
network. protocol-handler. external-default Boolean Determines the default action for unlisted external protocol handlers
True (default): Try to load
False: Opposite of the above
network. protocol-handler. external. (protocol) Boolean Determines whether to allow external protocol handlers to catch links with these protocols
True: Allow external handler to handle link
False (default): Prevent external handler from handling this link
network. protocol-handler. warn-external-default Boolean Determines whether to warn the user before loading an unlisted external handler
True (default): Warn the user
False: Opposite of the above
network. protocol-handler. warn-external. (protocol) Boolean Determines whether to warn the user before loading this protocol's external handler
True: Warn the user
False (default): Opposite of the above
network. proxy. autoconfig_url String The automatic proxy configuration URL used by the browser to determine a proxy server. Used when network.proxy.type is 2. Default value is an empty string.
Note: In Firefox, this can be changed via "Tools → Options → General → Connection Settings... → Automatic proxy configuration URL"
network. proxy. failover_timeout Integer Determines how long to wait until re-contacting an unresponsive proxy server. Default value is 1800 (30 minutes).
network. proxy. (protocol) String A manually configured proxy for the given protocol. Default value is an empty string.
Note: In Firefox, this can be changed via "Tools → Options → General → Connection Settings... → Manual proxy configuration"
network. proxy. (protocol)_port Integer The port for the manually configured proxy for the given protocol. Used when network.proxy.type is 1.
Note: In Firefox, this can be changed via "Tools → Options → General → Connection Settings... → Manual proxy configuration"
network. proxy. no_proxies_on String A comma-and-space-delimited list of hosts for which the specified proxies should not be used.
Note: In Firefox, this can be changed via "Tools → Options → General → Connection Settings... → Manual proxy configuration → No Proxy for"
network. proxy. share_proxy_settings Boolean Determines whether to use the same proxy server for all protocols.
True: Use one proxy for all protocols
False (default): Opposite of the above
Note: In Firefox, this can be changed via "Tools → Options → General → Connection Settings... → Manual proxy configuration → Use the same proxy for all protocols"
network. proxy. socks_remote_dns Boolean True: Perform all DNS lookups on remote proxy server (see bug 134105)
False (default): Perform all DNS lookups client-side
network. proxy. socks_version Integer Determines which version of SOCKS to use with the server specified in network.proxy.socks. Default value is 5. (The only other valid version is 4.)
network. proxy. type Integer Determines how the browser uses proxies.
0 (default): Direct connection to the Internet (no proxy used)
1: Manual proxy configuration (use values in network.proxy.*)
2: Autoconfiguration by URL (use value in network.proxy.autoconfig_url)
3: Same as 0 for compatibility reasons (see bug 115720) and will be reset to 0
4: Auto-detect proxy settings for this network
network. security. ports. banned String A comma-separated list of port numbers to disable in addition to the ports already disabled by default. (See Mozilla Port Blocking for more information.)
network. security. ports. banned. override String A comma-separated list of port numbers to enable, overriding the default port blocking. (See Mozilla Port Blocking for more information.)
network. standard-url. encode-utf8 Boolean Determines how URLs are encoded and sent
True (default in Firefox 1.5 and above): Always encode and send URLs as UTF-8
False (default in Firefox 1.0.x and below): Opposite of the above
network. standard-url. escape-utf8 Boolean Determines whether URLs with UTF-8 characters are escaped per the spec
True (default): Escape UTF-8 characters
False: Send URLs as they are

NGLayout.*

NGLayout stands for Next Generation Layout Engine. These preferences are largely low-level tweaks and debug options for how content appears in the browser.

Name Type Meaning of Values
nglayout. compatibility. mode Integer Force a compatibility mode instead of autodetecting.
0 (default): Use supplied DTD
1: Standards compliance mode
2: Quirks mode
nglayout. debug. checksum_xul_fastload_file Boolean True (default): Verify that the checksum of the XUL Fastload file hasn't changed since that file was last written to disk
False: Don't bother verifying the checksum
nglayout. debug. crossing_event_dumping Boolean True: In debug-enabled builds, output information about NS_MOUSE_ENTER/EXIT-related events to stdout when Caps Lock is on and nglayout.debug.event_dumping is true
False (default): Opposite of the above
nglayout. debug. disable_xul_cache Boolean True: Prevent Mozilla from caching any chrome-level XUL components (XUL, JavaScript, CSS).
False (default): Cache XUL components for better performance.
nglayout. debug. disable_xul_fastload Boolean True: Disable XUL Fastload caching the in-memory compiled XUL to file (xul.mfl, xul.mfasl)
False (default): Enable XUL Fastload (see bug 112064)
nglayout. debug. enable_xbl_forms Boolean True: Use XBL form controls
False (default): Opposite of the above
nglayout. debug. event_dumping Boolean True: In debug-enabled builds, output event-related information to stdout when Caps Lock is on
False (default): Opposite of the above
nglayout. debug. invalidate_dumping Boolean True: In debug-enabled builds, output information about invalidated objects/elements to stdout when Caps Lock is on
False (default): Opposite of the above
nglayout. debug. motion_event_dumping Boolean True: In debug-enabled builds, output information about NS_MOUSE_MOVE-related events to stdout when Caps Lock is on and nglayout.debug.event_dumping is true
False (default): Opposite of the above
nglayout. debug. paint_dumping Boolean True: In debug-enabled builds, output information about paint events to stdout when Caps Lock is on
False (default): Opposite of the above
nglayout. debug. paint_flashing Boolean True: In debug-enabled builds, flash painted elements/objects when Caps Lock is on
False (default): Opposite of the above
nglayout. events. dispatchLeftClickOnly Boolean Determines whether to dispatch left-click events only to content in the browser (chrome/XUL is exempt from the effects)
True (default): Dispatch only left-click events to browser content
False: Dispatch both left- and middle-click events
nglayout. initialpaint. delay Integer Determines time in milliseconds to wait before an initial reflow attempt during page rendering. Default value is 250. Synchronize with content.notify.interval for best performance.

Plugin.*

Name Type Meaning of Values
plugin. default_plugin_disabled Boolean True (default): When a plugin is needed, prompt the user
False: Don't prompt the user to install needed plugins
plugin. expose_full_path Boolean True: In about:plugins and navigator.plugins, reveal the full path to plugin files
False (default): Show only the plugin filename
plugin. override_internal_types Boolean True: Allow plugins to override internal imglib decoder MIME types in full-page mode
False (default): Opposite of the above
plugin. scan. 4xPluginFolder Boolean Controls the scanning of the Navigator 4.x directory for plugins. When pref is missing, the default is to pickup popular plugins such as Flash, Shockwave, Acrobat, and Quicktime. If set to true, ALL plugins will be picked up and if set to false the scan will not happen at all.
plugin. scan. (Plugin) String Name of plugin to scan for, with a minimum version specified. By default, this preference exists for Acrobat (5.0), QuickTime (5.0), SunJRE (1.3), and WindowsMediaPlayer (7.0).
plugin. scan. plid. all Boolean True (default): Locate plugins by the directories specified in the Windows registry for PLIDs (currently HKLM\Software\MozillaPlugins\xxxPLIDxxx\Path)
False: Opposite of the above

Print.*

Name Type Meaning of Values
print. always_cache_old_pres Boolean True: Cache old presentation when going into Print Preview
False (default): Opposite of the above
print. extend_native_print_dialog Boolean True (default): Extend the native dialog with information on printing frames.
False: Opposite of the above
Note: Firefox 1.5 and above only.
print. print_edge_(position) Integer Determines the distance from the (position) edge of the page to measure the margin. Default value is 0.
print. print_extra_margin Integer Determines an extra gap or margin in twips (90 twips is 1/8 of an inch) around the content of the page for Print Preview only. Default value is 90 (1/8").
print. print_(footer or header)(position) String At the given position in the header or footer, print one of the following:
&T: Title of the document
&U: URL
&D: Date/time
&P: Page number
&PT: Page number "of" total pages
(any string): A literal string with the above substitutions made
print. save_print_settings Boolean True (default): Save the print settings after each print job
False: Opposite of the above
print. show_print_progress Boolean True (default): Show the progress dialog when printing
False: Opposite of the above
print. use_global_printsettings Boolean True (default): Every browser window uses the same print settings
False: Each browser window uses its own settings, and changes in one window don't affect the others
print. use_native_print_dialog Boolean True (default): Use the native print dialog
False: Use the OS print dialog
Note: Windows-only
print. whileInPrintPreview Boolean True (default): Allow printing while in Print Preview screen
False: Opposite of the above

Privacy.*

Name Type Meaning of Values
privacy. item. cache Boolean True (default): Clear the cache when using the Sanitize feature (Firefox 1.5 and above only)
False: Do not clear the cache
Note: In Firefox 1.5, this can be changed via "Tools → Options → Privacy → Sanitize Settings..."
privacy. item. cookies Boolean True (default): Delete all cookies when using the Sanitize feature (Firefox 1.5 and above only)
False: Opposite of the above
Note: In Firefox 1.5, this can be changed via "Tools → Options → Privacy → Sanitize Settings..."
privacy. item. downloads Boolean True (default): Clear history of downloaded files when using the Sanitize feature (Firefox 1.5 and above only)
False: Opposite of the above
Note: In Firefox 1.5, this can be changed via "Tools → Options → Privacy → Sanitize Settings..."
privacy. item. formdata Boolean True (default): Clear all saved form data when using the Sanitize feature (Firefox 1.5 and above only)
False: Opposite of the above
Note: In Firefox 1.5, this can be changed via "Tools → Options → Privacy → Sanitize Settings..."
privacy. item. history Boolean True (default): Clear the history when using the Sanitize feature (Firefox 1.5 and above only)
False: Opposite of the above
Note: In Firefox 1.5, this can be changed via "Tools → Options → Privacy → Sanitize Settings..."
privacy. item. cookies Boolean True (default): Delete all cookies when using the Sanitize feature (Firefox 1.5 and above only)
False: Opposite of the above
Note: In Firefox 1.5, this can be changed via "Tools → Options → Privacy → Sanitize Settings..."
privacy. item. passwords Boolean True (default): Delete all saved passwords when using the Sanitize feature (Firefox 1.5 and above only)
False: Opposite of the above
Note: In Firefox 1.5, this can be changed via "Tools → Options → Privacy → Sanitize Settings..."
privacy. item. siteprefs Boolean Planned for future use.
privacy. popups. disable_from_plugins Integer Sets limits on popups generated from plugins (e.g. Flash)
0: lets all popups through
1: limits their number to dom.popup_maximum (even with popup blocker disabled)
2: blocks popups from plugins
Whitelisted sites will still be able to open popups, regardless this setting.
privacy. popups. firstTime Boolean True (default): The user has never hidden the popup blocker notification bar before, so show a dialog explaining the status bar icon
False: The user has been informed of the status bar icon
privacy. popups. policy Integer Determines the popup blocker behavior.
1: Allow popups
2: Reject popups
Note: Seems to be deprecated in favor of dom.disable_open_during_load
privacy. popups. showBrowserMessage Boolean True (default): Display a message at the top of the browser window when a popup has been blocked
False: Display a status bar icon to indicate when a popup has been blocked
privacy. popups. usecustom Boolean Seemingly unused.
privacy. sanitize. promptOnSanitize Boolean True (default): Prompt before performing a Sanitize operation (Firefox 1.5 and above only)
False: Sanitize without confirmation
Note: In Firefox 1.5 and above, this can be changed via "Tools → Options → Privacy → Sanitize Settings..."
privacy. sanitize. sanitizeOnShutdown Boolean True: Perform a Sanitize operation when closing the browser (Firefox 1.5 and above only)
False (default): Sanitize only when asked
Note: In Firefox 1.5 and above, this can be changed via "Tools → Options → Privacy → Sanitize Settings..."

Profile.*

Name Type Meaning of Values
profile. allow_automigration Boolean Determines how the Profile Manager handles automigration
True: Allow automigration
False (default): Opposite of the above
profile. confirm_automigration Boolean True (default): Ask user before performing an automigration
False: Opposite of the above
profile. manage_only_at_launch Boolean True: Only show the Profile Manager at program launch
False (default): Show Profile Manager at any time via menus
Note: In Firefox, there is no UI to access the Profile Manager from within the browser
profile. migration_behavior Integer Determines how the profile root is set.
0 (default): use NS_APP_USER_PROFILES_ROOT_DIR
1: create one based on the NS4.x profile root
2: Use value in profile.migration_directory (if empty, use NS_APP_USER_PROFILES_ROOT_DIR)
profile. migration_directory String Path to directory for migration. Default value is an empty string.
profile. seconds_until_defunct Integer Number of seconds to wait until the profile is considered defunct. Default value is -1 (never consider the profile defunct).

Security.*

Name Type Meaning of Values
security. OCSP. URL String Determines the URL to query for OCSP certificate verification/validation if security.OCSP.enabled is 2. Default value is an empty string.
Note: In Firefox, this can be changed via "Tools → Options → Advanced → Validation → OCSP → Service URL"
security. OCSP. enabled Integer Determines behavior of OCSP-based certificate verification/validation.
0 (default): Do not use OCSP for certificate validation
1: Use OCSP to validate only certificates that specify an OCSP service URL
2: Enable and use values in security.OCSP.URL and security.OCSP.signingCA for validation
Note: In Firefox, this can be changed via "Tools → Options → Advanced → Validation → OCSP"
security. OCSP. signingCA String Determines the name of the OCSP signing certificate authority to use if security.OCSP.enabled is 2. Default value is an empty string.
Note: In Firefox, this can be changed via "Tools → Options → Advanced → Validation → OCSP → Response Signer"
security. ask_for_password Integer Determines when Mozilla Mail should ask for the master password.
0 (default): Only the first time it's needed
1: Every time it's needed
2: Every n minutes, where n is the value in security.password_lifetime.
security. checkloaduri Boolean Pref removed (use CAPS instead). Previously:
Determines how to handle access across schemes (e.g., loading file: URLs from http: URLs)
True (default): Perform security checks and block access for insecure access
False: Opposite of the above
security. default_personal_cert String Determines the selection of a security certificate to present to web sites that require one.
Select Automatically (default): Automatically choose the certificate
Ask Every Time: Prompt user with a choice of certificate options every time
Note: In Firefox, this can be changed via "Tools → Options → Advanced → Certificates → Client Certificate Selection"
security. dialog_enable_delay Integer Amount of time to in milliseconds to disable buttons on security-sensitive dialog boxes. Default value is 2000.
security. directory String Seemingly unused.
security. enable_java Boolean True (default): Java is enabled
False: Opposite of the above
Note: In Firefox, this can be changed via "Tools → Options → Web Features → Enable Java"
security. enable_ssl2 Boolean True (default): SSL 2.0 is enabled
False: Opposite of the above
Note: In Firefox, this can be changed via "Tools → Options → Advanced → Security → Use SSL 2.0"
security. enable_ssl3 Boolean True (default): SSL 3.0 is enabled
False: Opposite of the above
Note: In Firefox, this can be changed via "Tools → Options → Advanced → Security → Use SSL 3.0"
security. enable.tls Boolean True (default): TLS 1.0 is enabled
False: Opposite of the above
Note: In Firefox, this can be changed via "Tools → Options → Advanced → Security → Use TLS 1.0"
security. password_lifetime Integer Determines how long (in minutes) to go without asking for the master password in Mozilla Mail when security.ask_for_password is 2. Default value is 30.
security. (ssl2 or ssl3). (cipher suite) Boolean True (default in all except the two below): The SSL 2.0 encryption type (cipher suite) is enabled
False: Opposite of the above
security. ssl3. rsa_null_sha Boolean True: Enable "No encryption with RSA authentication and an SHA-1 MAC" as a cipher suite
False (default): Opposite of the above
security. ssl3. rsa_null_md5 Boolean True: Enable "No encryption with RSA authentication and an MD5 MAC" as a cipher suite
False (default): Opposite of the above
security. ui. enable Boolean Seemingly unused.
security. warn_entering_secure Boolean True (default): Display a dialog warning the user when entering a secure site from an insecure one
False: Opposite of the above
security. warn_entering_secure. show_once Boolean True (default): Leave the "Alert me whenever..." box unchecked on the security warning dialog
False: Opposite of the above
security. warn_entering_weak Boolean True (default): Display a dialog warning the user when entering an insecure site from a secure one
False: Opposite of the above
security. warn_entering_weak. show_once Boolean True (default): Leave the "Alert me whenever..." box unchecked on the security warning dialog
False: Opposite of the above
security. warn_leaving_secure Boolean True (default): Display a dialog warning the user when leaving a secure site
False: Opposite of the above
security. warn_leaving_secure. show_once Boolean True (default): Leave the "Alert me whenever..." box unchecked on the security warning dialog
False: Opposite of the above
security. warn_submit_insecure Boolean True (default): Display a dialog warning the user when submitting a form to an insecure site
False: Opposite of the above
security. warn_submit_insecure. show_once Boolean True (default): Leave the "Alert me whenever..." box unchecked on the security warning dialog
False: Opposite of the above
security. warn_viewing_mixed Boolean True (default): Display a dialog warning the user when a page has both encrypted and non-encrypted content
False: Opposite of the above
security. warn_viewing_mixed. show_once Boolean True (default): Leave the "Alert me whenever..." box unchecked on the security warning dialog
False: Opposite of the above
security. xpconnect. plugin. unrestricted Boolean True (default): Allow scripting of plugins by untrusted scripts
False: Opposite of the above

Signon.*

Name Type Meaning of Values
signon. SignonFileName String Determines the filename that the Password Manager uses for storing signon data. Default value is signons.txt.
signon.expireMasterPassword Boolean True: The master password for the Password Manager will expire
False (default): Opposite of the above
signon. rememberSignons Boolean True (default): Enable the Password Manager
False: Opposite of the above

Snav.*

These preferences are associated with Spatial Navigation, a method of moving focus on a web page with respect to the visual layout of elements. Spatial navigation is not present (compiled in) by default, so these preferences will only work in binaries compiled with ac_add_options --enable-extensions=spatialnavigation.

Name Type Meaning of Values
snav. directionalBias Integer When calculating distances between elements on the screen, elements may be given a bias if the elements are in the direction of navigation. The bias is a given by a fraction such that:
bias distance = true distance / directional bias. The default value is 3.
snav. disableJS Boolean True (default): Disable onFocus event that an element may recieve during spatial navigation. On some pages the page decides to move the focus as if the targeted content was clicked. This may lead to an undesirable behavior.
False: Honor onFocus handlers triggered by spatial navigation
snav. enabled Boolean True (default): Enable spatial navigation
False: Opposite of the above
snav. ignoreTextFields Boolean True (default): Ensure that text fields and inputs retain focus even if spatial navigation was requested
False: Opposite of the above
snav. keyCode. down String Determines the key code corresponding to downwards spatial navigation. Default value is DOM_VK_DOWN. (A complete listing of possible key codes is available in nsIDOMKeyEvent.idl.)
snav. keyCode. left String Determines the key code corresponding to left spatial navigation. Default value is DOM_VK_LEFT. (A complete listing of possible key codes is available in nsIDOMKeyEvent.idl.)
snav. keyCode. modifier String Determines the key code corresponding to the required modifier keys. These values are given as follows:
NONE: 0
SHIFT: 0x00100000
CONTROL: 0x00001100
ALT: 0x00000012
The default value is ALT | SHIFT.
snav. keyCode. right String Determines the key code corresponding to right spatial navigation. Default value is DOM_VK_RIGHT. (A complete listing of possible key codes is available in nsIDOMKeyEvent.idl.)
snav. keyCode. up String Determines the key code corresponding to upwards spatial navigation. Default value is DOM_VK_LEFT. (A complete listing of possible key codes is available in nsIDOMKeyEvent.idl.)
snav. rectFudge Integer To reduce the chance that a element overlaps with another element, we reduce the elements height and width by this value. Default value is 20.

UI.*

Most of these preferences control settings that the browser attempts to read from the host operating system (e.g., your current color scheme). However, these can be overridden by manually setting the preferences to something else. For a more complete listing of the UI.* preferences, see UI Widget Look and Feel.

Name Type Meaning of Values
ui. key. accelKey Integer Determines the key code corresponding to the accelerator key.
17 (default in Windows): Ctrl
18 (default in BeOS): Alt
224 (default in Mac OS X): Cmd
ui. key. generalAccessKey Integer Determines the key code corresponding to the generic key used for Mozilla shortcuts
17 (default in BeOS, Mac OS X): Ctrl
18 (default in Windows): Alt
ui. key. menuAccessKey Integer Determines the key code corresponding to Mozilla menu access
0 (default in Mac OS X): none
17 (default in BeOS): Ctrl
18 (default in Windows): Alt
ui. key. menuAccessKeyFocuses Boolean True (default in Windows): Menus gain focus when ui.key.menuAccessKey is pressed
False: Opposite of the above
ui. key. saveLink. shift Boolean True (default): Shift-clicking a link opens the Save Link As dialog
False: Opposite of the above
ui. submenuDelay Integer Determines the delay in milliseconds between hovering over a menu option with a submenu and the submenu appearing. If this preference is not set, the OS's value is used.
ui. textSelectBackground String Determines the background color to use for text selections as a hex code or named color. If this preference is not set, the OS's value is used.
ui. textSelectBackgroundAttention String Determines the background color used for Find As You Type as a hex code or named color. If this preference is not set, the inverse of ui.textSelectBackground is used.
ui. textSelectForeground String Determines the text color to use for text selections as a hex code or named color. If this preference is not set, the OS's value is used.

Update.*, Update_notifications.*

Name Type Meaning of Values
update. interval Integer Determines how often to check extensions.update.interval and app.update.interval in seconds. Default value is 3600000 (1 hour).
update. severity Integer Used by the update system to determines when to display the icon for pending updates.
0 (default): Low severity update(s) available (extension/theme updates)
1: Medium severity update(s) available (numerous extension/theme updates)
2: High severity updates available (new version of Firefox/security patch)
update. showSlidingNotification Boolean True (default): Display the sliding alert when updates are available
False: Opposite of the above
update_notifications. enabled Boolean True (default): Display a notification in the browser when updates are available
False: Opposite of the above
update_notifications. provider. 0. datasource String Determines where to get update notifications. Value is pulled from chrome://browser-region/locale/region.properties.
update_notifications. provider. 0. frequency Integer Number of days between update checks. Default value is 7.

XPInstall.*

Name Type Meaning of Values
xpinstall. dialog. confirm String Determines the chrome location of the XPInstall dialog. Default value is chrome://mozapps/content/xpinstall/xpinstallConfirm.xul.
xpinstall. dialog. progress. chrome String Determines the chrome location of the extensions dialog. Default value is chrome://mozapps/content/extensions/extensions.xul?type=extensions.
xpinstall. dialog. progress. skin String Determines the chrome location of the themes dialog. Default value is chrome://mozapps/content/extensions/extensions.xul?type=themes.
xpinstall. enabled Boolean True (default): Enables the XPInstall system (i.e., allows extensions to be installed)
False: Opposite of the above
Note: In Firefox, this can be changed via "Tools → Options → Web Features → Allow web sites to install software"
xpinstall. whitelist. add String A comma-separated list of sites to automatically add to the extensions whitelist. Default value is update.mozilla.org,addons.mozilla.org but is cleared as soon as the values are added to the whitelist
xpinstall. whitelist. required Boolean True (default): When installing extensions from remote hosts, remote host must be on the whitelist
False: Opposite of the above

Miscellaneous

Name Type Meaning of Values
allinonegest. * Varied These preferences are set via the All in One Mouse Gestures extension.
application. use_ns_plugin_finder Boolean True: When a plugin is not found, clicking on the puzzle piece will open a dialog telling the user what plugin is needed. Clicking on the "Get the Plugin" button brings the user to the plugins installation page.
False (default): Clicking on the puzzle piece will send the user to that plugin's page on plugins.netscape.com which will have a link to that plugin's installation page.
backups. number_of_prefs_copies Integer Unused (obsolete). Previously: number of backup copies of prefs.js to keep.
clipboard. autocopy Boolean True: Selecting text automatically copies it to the clipboard
False (default): Opposite of the above
Note: *nix only.
converter. html2txt. header_strategy Integer How to format HTML headers (H1-H6) when saving a web page as text-only
0: No indentation
1 (default): Indent headers based on header level (i.e. H(n+1) is indented more than H(n))
2: Number headings and indent slightly
converter. html2txt. structs Boolean Determines whether to format "structured" elements (<strong>, <em>, <code>, <sub>, <sup>, <b>, <i>, <u>) with other characters when saving a web page as text-only
True (default): *Strong*, /em/, |code|, _sub, ^sup, *b*, /i/, _u_
False: Strong, em, code, sub, sup, b, i, u
custtoolbar. personal_toolbar_folder String Custom name for the Personal Toolbar Folder. If empty (default), name is determined by string bundle or the hard-coded value "Personal Toolbar Folder".
image. animation_mode String Determines how to animate multi-frame GIF images
none: animated images will never play.
once: animated images will play once.
normal (default): animated images will play as normal.
images. dither String Whether to dither images
auto (default): Automatically decide
true: Dither images
false: Disable image dithering
ime. password. onBlur. dontCare Boolean Determines how an IME editor window should react when password fields lose focus (see bug 16940).
True: Leave the IME open
False (default): Re-open the IME if it was open prior to the password field's focus.
Note: Firefox 1.5 and above only.
ime. password. onFocus. dontCare Boolean Determines how an IME editor window should react when password fields gain focus (see bug 16940).
True: Leave the IME open
False (default): Close the IME.
Note: Firefox 1.5 and above only.
inspector. * Varied These entries apply to the DOM Inspector and are only relevant if you have it installed.
keyword. URL String URL to use for keyword lookups. Default value is http://www.google.com/search?btnI=I%27m+Feeling+Lucky&ie=UTF-8&oe=UTF-8&q= in Firefox 1.0.
keyword. enabled Boolean Determines whether to use keywords
True (default): Send non-URLs entered in the Location Bar to the URL specified in keyword.URL
False: Disable keywords
mail. ui. display. dateformat. today Integer See Change the Date Format.
permissions. default. image Integer Determines when images should be loaded.
0 (default): Load all images
1: Load images from same (originating) server only
2: Do not load any images
Note: This preference was previously known as network.image.imageBehavior prior to Firefox 1.5.
pfs. datasource. url String Determines where the plugin finder service should query for plugin information. Default value is pulled from chrome://mozapps/locale/plugins/plugins.properties
prefs. converted-to-utf8 Boolean True: The preferences have been converted to UTF-8; decode as appropriate
False (default): Opposite of the above
roaming. default. files String A comma-separated list of files that will be selected for roaming by default. Default value is bookmarks.html,abook.mab,cookies.txt.
roaming. showInitialWarning Boolean True (default): Display a general warning to the user about making backups, security, etc.
False: Opposite of the above
signed. applets. codebase_principal_support Boolean True: Give scripts using codebase principals access advanced scripting capabilities. Setting this preference to "true" is often used to allow IRC websites to gain access to the OS's clipboard at the expense of a security risk.
False (default): Only trusted/signed scripts can access advanced scripting capabilities
Note: file: and resource: schemes are considered "special" and may get extra capabilities regardless of this preference's setting.
slider. snapMultiplier Integer Determines the size of the scrollbar snapping region. Default value is 6 in Windows; 0 (disabled) in *nix.
svg. enabled Boolean True (default): On SVG-enabled builds, renders SVG content
False: Opposite of the above (see bug 258511)
view_source. syntax_highlight Boolean True (default): Enable syntax highlighting in the view source window.
False: Opposite of the above
Note: This can be changed via "View → Syntax Highlighting" in the view source window.
view_source. wrap_long_lines Boolean True: HTML code will wrap in the view source window.
False (default): HTML code will not wrap in the view source window.
Note: This can be changed via "View → Wrap Long Lines" in the view source window.
viewmanager. do_doublebuffering Boolean Determines whether the viewmanager should do double-buffering by default (see bug 169483).
True: Do double-buffering
False (default): Opposite of the above