The correct title of this article is about:config entries . It appears incorrectly here due to technical limitations in the wiki software.

This is not the place to edit your configuration settings. This is a reference to the entries in about:config, where all user preferences can be viewed and modified. In most cases the list below doesn't state whether a given preference applies to all, or only some (and which), of Firefox, Thunderbird, Mozilla Suite, SeaMonkey, or even the now discontinued Sunbird: trial and error is often the only way to tell if some particular preference applies to your version of your application.

Users not already familiar with about:config entries should read the companion article, about:config, which describes how to modify values and work with the about:config list.

This article does not contain a complete list of all preferences. If you don't find an entry below for a given preference, check the Category:Preferences (multiple-page) listing, which includes many new preferences that have not been added here, as well as those preferences that have been migrated from sections of this article. Also check Mail and news settings for a listing of Thunderbird and Mozilla Suite/SeaMonkey mail and news preferences. Alternative lists can be found here:

(For a comparison view of table and actual about:config settings, use the Fox Splitter (formerly Split Browser) extension or the new version of Fox-Splitter to show one above the other. Also, finding item documentation for a preference from within about:config can be sped up with the Prefsearch extension, which adds a context menu item to search Google for the selected preference item.)

Note: There is no indication in the table as to which items will take effect immediately, with a new window, or require restarting.

Spaces between the dots in preference names on this page 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.

accessibility.* allows you to modify Find As You Type behavior, change how the [Tab] key works in web pages and XUL, turn on caret browsing, and tweak other accessibility-related features.

accessibility.* has been migrated to Category:Preferences.

advanced contains two prefs: Advanced.mailftp and Advanced.system.supportDDEExec.

advanced.* has been migrated to Category:Preferences.

alerts. contains three prefs, all related to the GUI: Alerts.slideIncrement, Alerts.slideIncrementTime, and Alerts.totalOpenTime.

alerts.* has been migrated to Category:Preferences.

app.* allows you to modify application update behaviour.

app.* has been migrated to Category:Preferences.

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: This can be changed in Firefox via "Tools → Options → Content / Fonts & Colors → Colors... → Link Colors → Unvisited Links" (Firefox 1.5 and above) and via "Edit → Preferences → Appearance → Colors / Link Colors → Unvisited Links" in Mozilla Suite and SeaMonkey.

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: See bug 301248 (Mozilla Suite)

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. 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. 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. 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: Overwrite the current bookmarks.html file with the default set of bookmarks.

False (default): Do not reset bookmarks.

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 → Organize (or 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 → Organize (or 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 → Advanced → Network / Offline Storage" (Firefox3), Tools → Options → Advanced → Network / Cache" (Firefox 2) or "Tools → Options → Privacy → Cache (Firefox 1.5 and earlier); in Mozilla Suite/SeaMonkey, via "Edit → Preferences → Advanced → 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 parent directory of the Cache folder used for storing the browser's cache. In Windows, the path separator must be two backslashes (e.g. " C:\\Path\\To\\Parent\\Folder ") if the value is being set in the user.js or prefs.js instead of within about:config.

browser. cache. disk_cache_ssl Boolean True (default): Cache content received via SSL

False: Do not cache content received via SSL

Note: See bug 531801 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 and SeaMonkey 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 explicitly set, and XUL error pages. Default value is #FFFFFF .

Note: In Firefox, this can be changed via "Tools → Options → Content / Fonts & Colors → Colors... → Text and Background → Background " (Firefox 1.5 and above).

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 → Content / Fonts & Colors → Colors... → Text and Background → Text" (Firefox 1.5 and above).

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 Firefox 1.5 only DPI of display device. Affects CSS absolute length units (e.g. pt, mm).

-1 (default): Use the operating system's logical resolution or 96 DPI, whichever is greater

0: Force use of operating system's logical resolution

(n): Assume screen DPI of n. Default DPI is 96.

Note: In Firefox, this can be changed via "Tools → Options → Content → Advanced → Display Resolution". See browser. screen_resolution for Firefox 1.0.x or layout. css. dpi for Firefox 2.0+.

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 → Content / Fonts & Colors → Colors → Allow pages to chose their own colors, instead of my selections above" (Firefox 1.5 and above).

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 → Content / Fonts & Colors → Advanced → Allow pages to chose their own fonts, instead of my selections above" (Firefox 1.5 and above).

In SeaMonkey, the corresponding setting is Edit → Preferences → Appearance → Fonts → [√] Allow documents to use other 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 → Content / Fonts & Colors → Colors → Use system colors" (Firefox 1.5 and above).

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 aggressive 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: the desktop

1 (default): the downloads folder

2: the last folder specified for a download

Note: In Firefox, this can be changed via "Tools → Options → Main / Downloads → Save files to... (Firefox 2 and above) or Downloads/Download Folder → Save all files to this folder" (Firefox 1.5).

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 → Main / Downloads → Close it when all downloads are finished" (Firefox 2 and above) or Downloads / Download Manager → Close the Download Manager when all downloads are complete" (Firefox 1.5).

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 / History → Remember what I've downloaded" (Firefox 2 and above) or "Privacy → Download History → Remove files from the Download Manager" (Firefox 1.5).

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. scanWhenDone Boolean True (default): Scan files for viruses when they finish downloading

False: Do not scan downloads for viruses

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 → Main / Downloads → Show the Downloads window when downloading a file" (Firefox 2 and above) or "Tools → Options → Downloads / Download Manager → Show Download Manager when a download begins" (Firefox 1.5)

browser. download. manager. skipWinSecurityPolicyChecks Boolean True: Bypass the Windows security check (ignore system security settings for executable file downloads).

False: (default) Use Windows' security setting for executable file downloads ("Launching applications and unsafe files" setting in Internet Options). This blocks executable file downloads if the Windows setting is set to "Disable".

Note: Added in bug 445158 for Firefox 3 (3.0.6, 3.1b2 and above). No longer used in Firefox 3.6 and above (removed in bug 504804).

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.

Note: This was removed in bug 439495 for Firefox 3.1.

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 → Main / Downloads → Always ask me where to save files (Firefox 2 and above) or Downloads / Download Folder → Ask me where to save every file" (Firefox 1.5)

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 → General → Resize large images to fit in the browser window (Firefox 1.0.x and 1.5)". UI removed in Firefox 2.0+.

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. fixup. use-utf8 Boolean Firefox 11 / SeaMonkey 2.8 and above only. See bug 647403.

Default: false (but true on zh-TW localized builds).

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 / History → Remember what I enter in forms and the search bar" (Firefox 2 and above) or "Tools → Options → Privacy → Saved Forms → Save information I enter in forms and the Search Bar" (Firefox 1.5)

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. fullscreen. animateUp Integer Controls toolbar and tab strip animation while in Full Screen.

0: No toolbar and tab strip animation

1 (default): Animates only first collapse.

2: Animates each collapse.

browser. fullscreen. autohide Boolean Hides toolbar and tab strip when entering Full Screen.

True (default): Shows toolbar and tab strip.

False: Hides toolbar and tab strip

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. deleteTempFileOnExit Boolean True: Delete temporary files on exit. See comment 19 on bug 238789 (especially Mac)

False (same as default unset): Opposite of above (keep the files)

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 maximum days to remember visited pages in history. Default value is 9 for SeaMonkey and Firefox 2, 180 for Firefox 3.

Note: In Firefox 2, this can be changed via "Tools → Options → Privacy → History → Remember visited pages for the last ___ days". No UI for Firefox 3.

browser. history_expire_days_min Integer Number of minimum days to remember visited pages in history. Default value is 90.

Note: In Firefox 3, this can be changed via “Keep my history for at least ___ days” under “Tools → Options → Privacy → History”

browser. history_expire_sites Integer Maximum number of websites to keep in history. Default value is 40000.

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 (default in SeaMonkey): Opens external links in a new window

3 (default in Firefox): Opens external links in a new tab in the most recent window

1 (or anything else): Opens external links in current window

Note: In Firefox 1.5, this can be changed via "Tools → Options → Tabs → Open links from other applications in:"; in Firefox 2 and above, via “Tools → Options → Tabs → New pages should be opened in:” (same as browser.link. open_newwindow) and in SeaMonkey, via "Edit -> Preferences -> Navigator -> Tabbed browsing / Links from other applications -> Open links passed from another applications in". Pref removed from Firefox 3.5

browser. link. open_newwindow Integer Where to open links that would normally open in a new window

2 (default in SeaMonkey and Firefox 1.5): In a new window

3 (default in Firefox 2 and above): In a new tab

1 (or anything else): In the current tab or window

Note: In Firefox 1.5, this can be changed via "Tools → Options → Tabs → Force links that open new windows to open in:"; in Firefox 2 and above, via “Tools → Options → Tabs → New pages should be opened in:” (same as browser.link.open_external) and, in SeaMonkey, via "Edit -> Preferences -> Navigator -> Tabbed browsing / Link open behavior -> Open links meant to open a new window in".

browser. link. open_newwindow. restriction Integer Firefox and SeaMonkey only. Source: The Burning Edge.

0 (Default in Firefox 1.0.x and SeaMonkey): 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 (Default in Firefox 1.5 and above): 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. microsummary. enabled Boolean True (default): Allow the microsummary service to retrieve information for bookmarks with microsummaries.

False: Prevent microsummary updates to bookmarks.

browser. microsummary. generatorUpdateInterval Integer Determines how often to check for updates to microsummary generators when generator updates are enabled. A non-negative integer, in seconds, determining the amount of time between microsummary generator update checks. If unspecified, updates occur weekly (7 * 86400 seconds apart).

browser. microsummary. requestTimeout Integer Determines how long to wait for a response until the connection is cancelled. A positive integer determining the number of seconds to wait until cancelling microsummary loads that take too long. Default value is 300.

browser. microsummary. updateGenerators Boolean True (default): Periodically check for updates to microsummary generators.

False: Do not update microsummary generators.

browser. microsummary. updateInterval Integer Determines how often microsummaries’ target pages are re-fetched for new information. Number of minutes between microsummary updates for microsummaries that do not specify an update interval. Default is 30.

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. places. createdDefaultQueries Boolean True: A "Most Viewed" folder in the Bookmarks Toolbar Folder has been created already; do not create a new one.

False (default): Create a "Most Viewed" folder in the Bookmarks Toolbar Folder, then toggle this preference to True.

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.



Applies to: Firefox 1.5 and above

SeaMonkey 2 dated 20071028 and later, for preferences migrated to "new toolkit".

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. safebrowsing. dataProvider Integer The provider ID of the site used to get the web forgery list. Default value is 0.

Note: This references the pref tree browser.safebrowsing.provider.*

browser. safebrowsing. enabled Boolean Whether to determine if a site is a web forgery or not.

True (default): Check visited sites

False: Do not check any sites

Note: This can be changed in Firefox via "Tools → Options → Security / Tell me if the site I'm visiting is a suspected forgery".

browser. safebrowsing. provider. * Tree Tree containing provider information used in the safe browsing process.

Note: There is currently only one default provider (Google); however, more may be added.

browser. safebrowsing. remoteLookups Boolean Method to determine if a site is a web forgery.

True: Ask provider by sending a request

False (default): Use internal list

Note: This can be changed in Firefox via "Tools → Options → Security" radio buttons:

* "Check using a downloaded list of suspected sites" (False)

* "Check by asking ____ about each site I visit" (True).

Note: When an internal list is used, it is updated about once an hour from the provider.

browser. safebrowsing. warning.infoURL String The FAQ URL for the Safe Browsing feature.

browser. screen_resolution Integer Firefox 1.0.x only DPI of display device. Affects CSS absolute length units (e.g. pt, mm).

-1 (default): Use the operating system's logical resolution or 96 DPI, whichever is greater

0: Force use of operating system's logical resolution

(n): Assume screen DPI of n. Default DPI is 96.

Note: In Firefox 1.0.x, this can be changed via "Tools → Options → General → Fonts & Colors → Display Resolution". See browser. display. screen_resolution for Firefox 1.5.0.x or layout. css. dpi for Firefox 2.0+.

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. log Boolean True: Log debugging information about the search service to the JavaScript Console and stdout .

False (default): Do not log debugging information.

Note: Firefox 2.0 and above only.

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. showOneOffButtons Boolean True (default): field of unlabeled search icons covering viewing area when typing into search bar (introduced in Firefox 34)

False: Restore pre Firefox 34 search engine drop-down selection and customization menu. Restart Firefox to effect change.

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_total_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_total_viewers Integer Determines the maximum number of content viewers to cache for "bfcache" (fast back/forward navigation). Default value is -1 (calculate based on available memory). All values less than 0 are equivalent.

Note: Firefox 1.5 and above only. Supersedes browser.sessionhistory.max_viewers.

browser. sessionhistory. max_viewers Integer The number of content viewers to cache for "bfcache" (fast back/forward navigation). Default value is 3.

Note: Deer Park/Firefox 1.5b1 only. Functionality has been replaced by browser.sessionhistory.max_total_viewers.

browser. sessionstore. max_concurrent_tabs Integer Firefox 4.0b7 and above; also SeaMonkey

<0: All tabs may restore at the same time.

=0: Only the current tab in each window will load ("load-on-demand" feature).

>0: Number of tabs which may restore at the same time.

Default value is 3.

browser. shell. checkDefaultBrowser Boolean Check the system 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 → Main / System Defaults" (Firefox 2.0 and above) or "Tools → Options → General → Default Browser" (Firefox 1.5 and 1.0.x).

browser. startup. homepage String URL of homepage, or pipe ( | )-separated list of URLs to open in tabs when going to the homepage

In SeaMonkey (or at least in SeaMonkey 2 and above), this is the URL of your first or only homepage tab. If you have a multitab homepage, additional URLs are in browser.startup.homepage.1, browser.startup.homepage.2, etc.

Note: This can be changed in Firefox via "Tools → Options → Main (Firefox 1.5 and 1.0.x: General) → Homepage" and in SeaMonkey via "Edit → Preferences → Browser → Home Page".

browser. startup. homepage. count Integer In SeaMonkey, the number of tabs of your multitab homepage, or 1 if you use a single-tab 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 (works in Firefox 2 and above; experimental in the latest nightlies of SeaMonkey 2.0b1pre; probably doesn't work in earlier versions).

Note: This can be changed in Firefox via "Tools → Options → Main → Startup → When Firefox starts", and in SeaMonkey via "Edit → Preferences → Browser → Display on → Browser startup".

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 → Tabs → Always show the tab bar" (Firefox 2 and above) or Tools → Options → Tabs → Hide the tab bar when only one web site is open (Firefox 1.5).

browser. tabs. closeButtons Integer (Firefox 2.0 and above) This preference controls how close buttons can be displayed on tabs.

0: Display a close button on the active tab only

1: (default) Display a close button on each tab

2: Don't display any close buttons

3: Display a single close button at the end of the tab bar (Firefox 1.x behavior)

Note: Firefox 31 removed these choices, install tabs closebutton restored to restore these options.

browser. tabs. closeWindowWithLastTab Boolean (Firefox 3.5 and above) This preference controls whether closing the last tab, closes the window.

True: Close window when closing last tab (default)

False: Do not close the window when closing last tab (pre Firefox 3.5 behavior)

Note: Changing to False prevents Firefox from closing the window when you close the last tab such as with Ctrl+W, and subsequently from closing Firefox itself when closing the last tab of the last Firefox window.

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. insertRelatedAfterCurrent Boolean (Firefox 3.6 and above) This preference controls where new tabs will be located.

True (default): Open new tabs to the right of the parent tab.

False: Restores pre Firefox 3.6 behavior where new tabs are opened at the far right of the tabs bar.

Note: Bug 465673 -- tabs opened from links should appear next to the current tab (instead of at the end of the tabstrip)

browser. tabs. loadBookmarksInBackground Boolean Focus behavior of new tabs from bookmarks & history

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: you likely want to set this to the same setting value as used in browser.tabs.loadInBackground (Bug 469456)

Note: Firefox 1.0.x had a Tabs option for "Select New Tabs from Bookmarks or History"

browser. tabs. loadDivertedInBackground Boolean Determines behavior of pages normally meant to open in a new window (such as target="_blank" 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. Note: target="_new" creates/reuses a window named "_new" and is frequently used by Google. target="_blank" loads the designated document in a new, unnamed window [ [1]].

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.

Note: This option was removed in Firefox 3 alpha 8.

browser. tabs. loadGroup Integer 0: Append group to current tab set

1 (default): Replace current tab set with group

Note: Mozilla Suite/SeaMonkey only.

browser. tabs. loadInBackground Boolean Focus behavior for new tabs from links

True (default): Do not focus new tabs opened from links (load in background)

False: Opposite of above

Note: bookmarks & history can be opened similarly with browser.tabs.loadBookmarksInBackground

Note: In Firefox, this can be changed via "Tools → Options → Tabs → When I open a link in a new tab, switch to it immediately" (Firefox 2 and above) or "Tools → Options → Tabs → Select new tabs opened from links" (Firefox 1.5).

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 (see bug 269664).

browser. tabs. onTop Boolean (Firefox 4.0 and above) Determines position of the Tabs Bar relative to the Location Bar.

True (default): Tabs Bar above Location Bar

False: Restores old behavior of Tabs Bar below Location Bar

Note: bug 755593 will soon remove tabs-on-bottom mode. Once it is RESOLVED FIXED, this pref will no longer be effective.

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 Pref removed (unused). Previously:

Determines the behavior of pressing Enter in the address bar or clicking the Go button.

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. 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 than one tab.

Note: In Firefox, this can be changed via "Tools → Options → Tabs → Warn (me) when closing multiple tabs" (Firefox 1.5 and above).

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. 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: This feature is currently only stable on trunk (1.9).

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 → Content → 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. autocomplete. enabled Boolean True (default)

False

browser. urlbar. clickAtEndSelects Boolean True (default)

False

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. default. behavior Integer Customizes the search behavior of the location bar, starting in Firefox 3.5 and SeaMonkey 2. See the linked article for values and UI.

browser. urlbar. doubleClickSelectsAll Boolean True: Select the contents of the address bar when it is double clicked

False(default): Opposite of above

browser. urlbar. filter. javascript Boolean True (default): Filter out “javascript:” URLs from appearing in the Location Bar autocomplete dropdown.

False: Allow “javascript:” URLs to appear in the dropdown.

browser. urlbar. formatting. enabled Boolean True (default): Format url in location bar to emphasize domain name.

False: Don't fade non domain portions of url in location bar.

browser. urlbar. match. title String See Location Bar search

browser. urlbar. match. url String See Location Bar search

browser. urlbar. matchBehavior Integer Determines how to use word boundaries when searching for items in the Location Bar.

0 Search anywhere within available text, irrespective of word boundaries.

1 (default): Use word boundaries first when searching, then try matching anywhere

2: Use only word boundaries when searching for typed text

3: Match only the beginning of page URLs and titles

browser. urlbar. matchOnlyTyped Boolean Determines behavior of autocomplete in Location Bar. No longer used in Firefox 3.5 - replaced by browser.urlbar.default.behavior (see bugs 463483 and 463558)

True: Only matches typing against URLs specifically typed into Location Bar

False (default): Match against history

browser. urlbar. matchOnWordBoundary Boolean Determines behavior of autocomplete in Location Bar

True (default): Use word boundaries when searching for typed text in the Location Bar autocomplete.

False: Search anywhere within available text, irrespective of word boundaries.

Obsoleted by browser. urlbar. matchBehavior.

browser. urlbar. maxRichResults Integer Determines how many entries should appear (at most) in the dropdown in Location Bar.

browser. urlbar. restrict. bookmark String See Location Bar search

browser. urlbar. restrict. history String See Location Bar search

browser. urlbar. restrict. tag String See Location Bar search

browser. urlbar. restrict. typed String See Location Bar search

browser. urlbar. search. chunkSize Integer Number of dropdowns to fetch at a time. Default is 1000.

browser. urlbar. search. timeout Integer Number of milliseconds to wait between fetching batches of dropdown items. Default is 100 (1/10th of a second).

browser. urlbar. showPopup Boolean True (default)

False

browser. urlbar. showSearch Boolean True (default)

False

browser. urlbar. trimURLs Boolean True (default): Trim "http://" prefix from url address displayed in location bar .

False: Don't trim url in location bar.

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 → Content → 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 and SeaMonkey): The browser will use error pages.

False (default in Firefox 1.0.x and below): The browser will use error alert boxes.

browser. zoom. full Boolean True (Default): Full page zoom

False: Text zoom