This page was created to be a companion of my page on Tabbed Browsing in Firefox.
The table on this page consisting of selected tab and window
items has been extracted from
which is part of the MozillaZine_Knowledge_Base article http://kb.mozillazine.org/MozillaZine_Knowledge_Base:About
Heuer's Razor: "If it can't be turned off, it's _not_ a feature." (is often quoted in Developer groups.)
This listing is basically comprised of entries selected from the mozillaZine article About:config entries http://kb.mozillazine.org/About:config_entries dealing with tabs and is mainly from the following groups:
To view table and your own settings at the same time, you might want to install the Split Browser extension and split the screen vertically with the table as the main at the bottom so it is with Find, and with the split about:config at the top, and descriptions such as on this page below. (for more information see firefox.htm page)
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.
To find values related to an about:config configuration entries
Use your browser's FIND to find variables or descriptions matching a one word or character string. For instance you might want to use FIND openintab in browser, and filter: openintab in the about:config list where "browser.search.openintab" has extra spaces as "browser. search. openintab".
To change a configuration setting double-click on the variable and change the value (right-click context menu also works). If the type is Boolean a double-click will toggle the value immediately, so always keep an eye on the value or the "user set" / "default" indication for each variable.
number rows Click once on the bookmarklet at the left to Number the rows of each table. Details of Text and Data Bookmarklets at squarefree.com also see my Keyword shortcuts page to invoke bookmarklets on any page.
|Name||Type||Meaning of Values|
|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. block. target_new_window||Boolean|| True: Links with target set to |
False: Links with target set to
Note: No longer in use. Use browser.link.open_newwindow instead.
|browser. display. focus_background_color||String|| The default color for the background of focused elements as a hex code. Default value is |
|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 |
|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. 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. link. open_external||Integer|| Where to open links sent to the browser from an
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 1.5, this can be changed via "Tools → Options → Advanced → Tabbed Browsing → Open links from other applications in:"
This option is mentioned under Browser Behavior in Firefox Help: Tips & Tricks
Possibly removed in Firefox 3.1 see bug: 324164
Bug 468973 - 3.1b2 doesn't honor browser.link.open_external = 2 (Open in New Window)
|browser. link. open_newwindow||Integer|| Where to open links that would normally open in
2: In a new window
3 (default): In a new tab
1 (or anything else): In the current window
|browser. link. open_newwindow. restriction||Integer|| Firefox and SeaMonkey only. Source: The Burning Edge.
This option is mentioned under Browser Behavior in Firefox Help: Tips & Tricks
|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. search. openintab||Boolean|| True: When performing a search from the
Bar, open the results in a new tab.
False (default): Open search results in the current tab/window.
Note: Firefox nightly trunk builds only.
If you foolishly installed Tab Mix Plus then controlled by extensions.tabmix.opentabfor.search
|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. 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.
|Browser. sessionstore. enabled||Boolean||True (default):
Record information about the current browser session (open windows and tabs, history, cookies, form data) so it can be restored if necessary.
False: Disable the Session Restore service completely.
* For the browser session to be restored at startup after a crash, browser.sessionstore.resume_from_crash must be true.
* For the browser session to be restored at startup normally, browser.startup.page must be 3.
|Browser. sessionstore. resume_from_crash||Boolean||
Firefox 2.0 introduces a built-in Session Restore feature, allowing the user to continue browsing from where they left off if browser restarts.
True (default): Restore the previous session when the browser starts after a crash.
False: Do not restore the previous session.
* browser.sessionstore.enabled must be true for this preference to have an effect.
* Related preferences: | browser.sessionstore.enabled | browser.sessionstore.interval | browser.sessionstore.max_tabs_undo | browser.sessionstore.max_windows_undo | browser.sessionstore.resume_session | browser.sessionstore.resume_session_once |
|browser. startup. homepage||String|| URL of homepage, or pipe (|
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.page||Integer||Each time the web browser starts, this preference is consulted to determine what to display. It has superseded browser.sessionstore.resume_session as the preference determining whether saved sessions are restored.
0: Start with a blank page (about:blank).
1: (default) Start with the web page(s) defined as the home page(s).
2: Load the last visited page.
3: Resume the previous browser session (Firefox only, implemented after Firefox 2 beta 1)
|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) 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)
|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. 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 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 (
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
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.
Even with the setting at True, if you don't want to lose the current tab, and want new tabs at end instead of adjacent to active tab use Ctrl+Shift+click on "Open all in Tabs" (or Ctrl+click ..., whichever shortcut will load new tab(s) in foreground is the only one that will work)
Bug 175124 - improve open in tabs behaviour,
|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)
|browser. tabs. loadOnNewTab||Integer|| Determines what will be displayed in a new tab
-1: Browser startup page
0 (default): Blank page
2: Last visited page
Note: Does not work in Firefox (see bug 269664).
Solutions: New Tab Homepage (7KB), or NewTabURL (47KB).
|browser. tabs. opentabfor. bookmarks||Boolean|| Controls if a clicked bookmark will open in a
Note: Pref removed (obsolete). Functionality proposed as enhancement request.
|browser. tabs. opentabfor. middleclick||Boolean|| Determines the behavior of a link when
True (default): Opens link in new tab
False: Opens link in new window
MenuEditor extension and Tab related extensions might remove control of Middle-click, since I don't use Firefox's middle-click -- can't tell whether true or not.
|browser. tabs. opentabfor. searchdialog||Boolean|| Determines whether to create a new tab for the
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. selectOwnerOnClose||Boolean||In conjunction with several other improvements to tabbed browsing in Firefox 2.0, the behavior of closing tabs was changed. Previously, closing any tab would shift focus to the tab immediately to the right if possible; failing that, the tab to the left. Now, if a page that would normally have opened in a new window is opened in a tab and that tab is closed, focus is shifted to the tab that opened the window. This preference controls whether the old or new behavior is observed.
True - If new windows are diverted into new tabs and a resulting tab is closed, shift focus back to the tab that opened it. (Default)
|browser. tabs. showSingleWindowModePrefs||Boolean|| Determines whether to display "Single Window
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 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) or "Tools → Options → Advanced → Tabbed Browsing → Warn when closing multiple tabs" (Firefox 1.0.x)
|browser. tabs. warnOnCloseOther||Boolean|| True (default): The browser will prompt
confirmation when closing all other tabs from the tab context menu
("Close Other Tabs")
False: Opposite of the above
|Browser.warnOnQuit||Boolean||When quitting Firefox via “File → Exit”, every open browser window will be closed. This preference determines (along with browser.tabs.warnOnClose) whether or not a warning dialog appears before this happens.
Possible values and their effects
True (default): Display a dialog before quitting, warning that all windows will be closed.
False: Do not require confirmation from the user when quitting.
Caveats - If browser.tabs.warnOnClose is false, then this preference has no effect.
|Browser. warnOnRestart||Boolean||True (default)
Display a dialog before restarting the browser, warning that all windows will be closed.
False Do not require confirmation from the user when restarting.
UI — A checkbox labeled “Do not ask next time” appears on the confirmation dialog; when checked, this preference is toggled to false.
|browser. windows. loadOnNewWindow||Integer|| Set what should be displayed in a newly created
-1: Browser Startup Page
0: Blank Page
1 (default): Your Homepage
2: Last Visited
|browser. zoom. full||Boolean|| True (Default): Full page zoom|
False: Text zoom
|browser. zoom. siteSpecific||Boolean|| True (Default): Remember the zoom level on a per-site basis.|
False: The zoom level should be applied on the current tab only.
|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
Ignore "location=no" in the window features argument of window.open() and prevent popups from hiding the Location Bar (Default in Fx3). False allows popups to hide the Location bar. (Default in Fx2) In Fx2 default was False, in Fx3 default is True.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.
Ignore "status=no" in the window features argument of window.open() and prevent popups from hiding the status bar. (Default);titlebar: Prevents the title bar from being hidden.
toolbar: Prevents the navigation toolbar from being hidden.
|toolkit. scrollbox. clickToScroll. scrollDelay||Integer||Determines how many milliseconds to wait before scrolling the tab strip by another increment. (Default: 150)|
|toolkit. scrollbox. scrollIncrement||Integer||Determines how many pixels to scroll at a time when scrolling the tab stripís scrollbox. (Default: 20)|
|toolkit. scrollbox. smoothScroll||Boolean|| True (default): Scroll the tab strip smoothly to a newly-selected tab.|
False: Move to the new tab immediately.
|view_source. tab_size||Integer||sets the width of a tab character in the view source window. Already open windows aren't updated (implemented in bug 295506 in trunk builds (mozilla-1.9.3a1) starting 2010-02-03)|
|Unrelated about:config options of interest|
|browser. bookmarks. autoExportHTML||Boolean||True -
Export bookmarks to bookmarks.html each time the browser shuts down.
False (default) - Do not export HTML at shutdown.
Will be needed for 3.1 and 3.2 so that Ctrl+Tab, Ctrl+Shift+Tab work browser.ctrlTab.previews removes tab preview
# Set browser.ctrlTab.mostRecentlyUsed to false (create name)
# Set browser.ctrlTab.recentlyUsedLimit to 0
also check these into table
loadDivertedInBackground is for external links, not bookmarks. There's a
loadBookmarksInBackground pref that has UI
How To Modify Hidden Preferences Using about:config[http://www.mozillazine.org/misc/about:config/]
having to use Alt+Enter. Should lead to groups of webpages that invoke
userstyles.org works with styling changes instead of hardcoded in userChrome.css
As interesting this concept is (see comment #41 there), it prevents use of bookmarklets from the location bar and from bookmarks, so is unusable. Possibly some code in
http://www.mozilla.org/unix/customizing.html has a solution
Some settings used and/or found in newsgroups (#settings)
|Name||Mine on 2007-01-22
using Firefox 2.0
No Tabs (Tab Killer)
and No Tabs
|browser. block. target_new_window||(user True)||False|
|browser. link. open_external||(default 3)||3 - New Tab||2 - New Window||1 - Current|
|browser. link. open_newwindow||(default 3)||3 - New Tab||2 - New Window||1 - Current|
|browser. link. open_newwindow. ui|
|browser. search. openintab||(user true)||false|
|browser. search. order.||(digit)|
|browser. tabs. autoHide||(user False)||false|
|Browser. tabs. closeButtons||(user 3 at right)|
|browser. tabs. forceHide||(default false)||false||True||True|
|browser. tabs. loadBookmarksInBackground||(default false)||false|
|browser. tabs. loadDivertedInBackground||(default False)||false|
|browser. tabs. loadFolderAndReplace||(user False)||false|
|browser. tabs. loadGroup||(default 1)||1|
|browser. tabs. loadInBackground||(default False)||false|
|browser. tabs. loadOnNewTab||(default 0)||0|
|browser. tabs. opentabfor. bookmarks|
|browser. tabs. opentabfor. middleclick||(default True) [see mouse]||true||false|
|browser. tabs. opentabfor. searchdialog||(**used when search bar is hidden)|
|browser. tabs. opentabfor. windowopen||(obsolete -- user False **)||N/A|
|browser. tabs. opentabfor. urlbar||(obsolete)||N/A||false (obsolete)|
|browser. tabs. showSingleWindowModePrefs||(default is False, determines whether to display "Single Window Mode" in preferences (see bug 266759)||false|
|browser. tabs. warnOnCloseOther||(default true)||tr12ue|
|browser. windows. loadOnNewWindow||(default 1)||1|
|(new tabs in immed before/after or at end)||(avail in humongous TMP)|
When you have finished changing your settings, test them out in the Target test area of Tabs page.
Page was originally edited by with Nvu and with Front Page as an experiment, don't like either of them. Updates are with Notepad like all my other pages, and use of CopyURL+ extension with a 3 column pattern may be used for some additions.
user_pref("copyurlplus.menus.12.copy", "<TR><td><a href=\"%URL_HTMLIFIED%\">%TITLE_HTMLIFIED%</a></td><td>Boolean |Integer |String</td><td>%SEL_HTMLIFIED%</td></tr> "); user_pref("copyurlplus.menus.12.label", "Tab documentation (3 columns)");
Modifying configuration entries should be intuitive, but more help is available at http://kb.mozillazine.org/About:config
I've landed bug 465076 today. The UI is now disabled on trunk. This is controlled by the browser.allTabs.previews and browser.ctrlTab.previews preferences. I'd like to encourage nightly testers and whoever's interested to flip both prefs and report bugs, so that we can make further progress there. I've filed bug 505404 for tracking these bugs. (2009-07-21, by Dao)
Firefox/Sprints/Control Tab - MozillaWiki
You can type about:support into the location bar to see ONLY changed settings. Change preferences are in the "Modified Preferences" section,
which is in alphabetical order.
For other sections you may have to sort table columns with a bookmarklet or with an extension.
An additional advantage to using the extension is that you can sort first on a minor sort and then on your major sort, the bookmarklet only gives you one column of sorting.
In your about:support list select the preference name, then use built-in search by right-clicking on selection and choosing "Search Google for ...." (uses your default search engine)
Most of the common user assigned preferences are in
if they relate to tabs, I probably have them here on this page, with additional information.
http://www.mvps.org/dmcritchie/firefox/tabs_config.htm (this page)
The Tab extensions that I currently use are simple extensions and should be good from one version of Firefox to another but if one should fail it would be a minor inconvenience compared to those that have choose Tab Mix Plus (xxx) and never know what actually is available in Firefox and better choices of extensions.
You can see my complete InfoLister listing of extensions I have currently installed (some are disabled), and you can find descriptions and usage notes for those and extensions I may have used in the extensions table within Firefox Customization (Notes) where you will find my notes on the following extensions. The extensions below total 198KB compared to the troublesome Tabs Mix Plus extension (417KB).
|browser.tabs.insertRelatedAfterCurrent||boolean||False -- will be needed for 3.6|