Firefox Desktop OSs about:config Modifications

In the following examples you will need to access Firefox's configuration page by setting in the address bar type 'about:config' (without the ) and then press enter, followed by clicking the 'I'll be careful, I promise' button.

To the right of 'Config name:' is the value to copy and paste in the 'about:config' 'Filter' bar.

To the right of 'Default:' is the original value.

To the right of 'Modified:' is the new value.

To modify a true/false config state double click on the Config name.

HOWTO: DISABLE:

Insecure Form Warning

Config name:	security.insecure_field_warning.contextual.enabled
Default:	true
Modified value:	false

Extensions Button v 109 >

Config name:	extensions.unifiedExtensions.enabled
Default:	true
Modified value:	false

Restart Firefox

DOM Storage

See here.

Config name:	dom.storage.enabled
Default:	true
Modified value:	false

However disabling DOM Storage can affect some sites, for instance the editing toolbar in MediaWiki (that runs this site) will disappear.

Firefox Stealing Focus When Opening Browser Links From An Email Client

If Firefox is your default browser then when you click on an URL in Thunderbird it is opened and Firefox springs to the foreground.

Config name:	browser.tabs.loadDivertedInBackground
Default:	false
Modified:	true

Image Resizing

If on opening a link to an image file it is too large to fit on screen by default Firefox reduces it to fit it all on screen. The following tweak disables this behaviour.

Config name:	browser.enable_automatic_image_resizing
Default:	True
Modified:	False

Location Aware Browsing (a.k.a. Geolocation) (v3.5 >)

Firefox uses its default geolocation service provider (Google) to determine the location of your computer using the following:

• the computer’s internet IP address
• information from nearby wireless access points
• a random client identifier (this is assigned by Google and expires every 2 weeks).

If you are concerned about your privacy this feature can be turned off in the following manner:

Config name:	geo.enabled
Default:	true
Modified:	false

Firefox prevented this page from automatically redirecting to another page

Config name:	accessibility.blockautorefresh
Default:	true
Modified:	false

Pocket Integration

Config name:	extensions.pocket.enabled
Default:	true
Modified:	false

Referrer Control

Config name:	network.http.sendRefererHeader
Default:	2
Modified:	0

Alternative:

If you have trouble accessing say a banks website try the following configuration instead:

Config name:	network.http.sendRefererHeader
Default:	2
Modified:	1

Screenshot Upload

Config name:	extensions.screenshots.upload-disabled
Default:	False
Modified:	True

Service Workers

Config name:	dom.serviceWorkers.enabled
Default:	True
Modified:	False

SSL3

Below are the settings to manually disable SSL3 protocols that are now considered insecure. While this can be done manually the latest versions of Firefox should disable them automatically and you can check this by looking at the following:

Config name:	security.tls.version.min
Default:	1

You can test the SSL safety of your browser at Poodle Test.

If you are completely paranoid and do not trust the above setting the following can be changed manually:

Config name:	security.ssl3.ecdhe_ecdsa_rc4_128_sha
Default:	true
Modified:	false

Config name:	security.ssl3.ecdhe_rsa_rc4_128_sha
Default:	true
Modified:	false

Config name:	security.ssl3.rsa_rc4_128_md5
Default:	true
Modified:	false

Config name:	security.ssl3.rsa_rc4_128_sha
Default:	true
Modified:	false

The following are considered to be slightly more secure but if erring on the side of caution modify them as well:

Config name:	security.ssl3.rsa_aes_128_sha
Default:	true
Modified:	false

Config name:	security.ssl3.rsa_aes_256_sha
Default:	true
Modified:	false

Config name:	security.ssl3.rsa_des_ede3_sha
Default:	true
Modified:	false

Tab Preview On Hover

Config name:	browser.tabs.hoverPreview.enabled
Default:	True
Modified:	False

Config name:	browser.tabs.hoverPreview.showThumbnails
Default:	True
Modified:	False

Tooltips

Config name:	browser.chrome.toolbar_tips
Default:	True
Modified:	False

Unified Complete

Config name:	browser.urlbar.unifiedcomplete
Default:	True
Modified:	False

Thanks to Ghacks.

Warning About Closing Other Tabs / Tabs To The Right

Config name:	browser.tabs.warnOnCloseOtherTabs
Default:	True
Modified:	False

Websites From Reading or Modifying Clipboard Contents

NOTE: This is a biggy, if you regularly copy text from inside a form field then this tweak is not for you.

Config name:	dom.event.clipboardevents.enabled
Default:	true
Modified value:	false

Thanks to Ghacks

HOWTO: ENABLE:

Autoscrolling (or Middle Button Scrolling)

Linux

Config name:	general.autoScroll
Default:	False
Modified:	True

Windows

Config name:	general.autoScroll
Default:	True
Modified:	False

Click-To-Play (v.15>)

Prevents some plugins from automatically playing content.

Config name:	plugins.click_to_play
Default:	false
Modified:	true

Hardware Acceleration

Config name:	layers.acceleration.force-enabled
Default:	False
Modified:	True

This option is to be enabled by default from version 57 onwards, but in version 53 it may be disabled depending on your platform.

Find Function Case Sensitive

Config name:	accessibility.typeaheadfind.casesensitive
Default:	0
Modified:	1

Open Search Box Results In New Tab

Config name:	browser.search.openintab
Default:	False
Modified value:	True

Prevent Firefox From Closing When Shutting The Last Tab (v3.5 >)

Config name:	browser.tabs.closeWindowWithLastTab
Default:	true
Modified:	false

Double click to toggle the value.

Prevent Firefox From Replacing Tabs When Using "Open All in Tabs"

When opening a folder of bookmarks using "Open All in Tabs", the currently displayed tabs are replaced. Creating this preference and setting it to 'True' will cause the new tabs to opened along side the current tabs.

New:	boolean
Config name:	browser.tabs.loadFolderAndReplace
Value:	True

Print Dialogue Window - Classic Style

Config name:	print.prefer_system_dialog
Default:	false
Modified:	true

Thanks to ASKVG.

Privacy Tracking Protection

Config name:	privacy.trackingprotection.enabled
Default Value:	false
Modified value:	true

Thanks to Ghacks

Private Browsing

Config name:	browser.privatebrowsing.autostart
Default Value:	false
Modified value:	true

Thanks to How To Geek

Spell Check All Text Boxes And Web Forms

Config name:	layout.spellcheckDefault
Default:	1 (spell checker for multi-lines text boxes only)
Modified:	0 (disable the spell checker)
Modified:	2 (enable the spell checker for all text boxes)

Tabs | New | Open On End

Config name:	browser.tabs.insertRelatedAfterCurrent
Default Value:	true
Modified value:	false

Tabs | Save On Exit Show/Quit Warning On Exit

By default FF4 does not offer to save open tabs when closing, this is a regression back to FF2 days. To turn on this option look under:

• Windows - Tools --> Options --> Tabs: Warn me when closing multiple tabs
• Linux - Edit --> Preferences --> Tabs: Warn me when closing multiple tabs
• Apple - Edit --> Preferences --> Tabs: Warn me when closing multiple tabs

If for any reason you find the corresponding box ticked but Firefox is still closing without the requisite warning try the following:

Config name:	browser.showQuitWarning
Default Value:	false
Modified value:	true

If the above does not work check that the following all have their values set to false:

Config Name:	browser.tabs.warnOnClose
Config Name:	browser.warnOnQuit
Config Name:	browser.warnOnRestart

WEBM Support

Config name:	media.mediasource.webm.enabled
Default Value:	false
Modified value:	true

HOWTO: MODIFY:

Address (URL) Bar Select All Text With One Click

Windows

Config name:	browser.urlbar.clickSelectsAll
Default:	true
Modified value:	false

Linux

Config name:	browser.urlbar.clickSelectsAll
Default:	false
Modified value:	true

Apple

Config name:	browser.urlbar.clickSelectsAll
Default:	true
Modified value:	false

Amount Of AwesomeBar Results (v.3 >)

The "AwesomeBar" allows you to do a keyword search of your bookmarks, tags and browsing history by typing in the address window. As you start typing in the address bar the AwesomeBar shows you a list of a dozen suggestion, this tweak allows you to set a higher or lower number of returns.

Config name:	urlbar.maxRichResults
Default:	12
Modified value:	6

Awesomebar Suggestions

When you type something into the Awesomebar, Firefox ranks its suggestions by something it calls "Frecency," a combination of how frequently and recently you visited a given URL. However, you can adjust the "weight" it gives to certain types of URLs—like bookmarks—with a few about:config tweaks.

For example that you wanted to give bookmarks a higher weight (so Firefox is more likely to suggest them near the top of the list) or no weight (so you don't see bookmarks at all in the Awesomebar suggestions).

The default value is 140, so if you want bookmarks to rank higher. increase this number. If you want them to rank lower, decrease this number, or set it to 0 to eliminate bookmark suggestions entirely. For more information, check out Mozilla's developer page and Knowledge Base article on frecency settings.

Config name:	places.frecency.unvisitedBookmarkBonus
Default:	140
Modified:	250 (more weight given to bookmarks)
Modified:	90 (less weight given to bookmarks)

Mercilessly filched from here.

Backspace Button Behaviour

Config name:	browser.backspace_action
Default:	2 (does nothing)
Modified:	0 (go back previous page)
Modified:	1 (page up)

Colour Of The Pin Tab Highlighting

~/.mozilla/firefox/5rdkbk74.NEW/userChrome.css

.tabbrowser-tab[pinned][titlechanged]:not([selected="true"]) { background: -moz-linear-gradient(hsla(0,0%,100%,.2), hsla(0,0%,45%,.2) 2px, hsla(0,0%,32%,.2) 80%) !important; }

.tabbrowser-tab[pinned][titlechanged]:not([selected="true"]):hover { background-image: -moz-linear-gradient(hsla(0,0%,100%,.6), hsla(0,0%,100%,.2) 4px, hsla(0,0%,75%,.2) 80%) !important; }

The above was pulled from here.

Context Menu Search Provider

This is when you highlight a piece of text and right click (context menu) then search. By default Firefox uses Google.com if you want to change it to another make sure you have that search engine provider installed.

Config name:	browser.search.defaultenginename
Default:	Google
Modified:	Google UK

Extension Install Delay

Config name:	security.dialog_enable_delay
Default:	2000
Modified:	0

Double click and alter to your choice. A value of '0' disables any delay.

Middle Button (Scroll Wheel) Paste

Linux

Config name:	middlemouse.paste
Default:	true
Modified:	false

Windows

Config name:	middlemouse.paste
Default:	false
Modified:	true

Apple

Config name:	middlemouse.paste
Default:	true
Modified:	false

Double click to toggle the value.

Plugins Control (v. 22>)

Plugins for programme extensions such as Adobe Flash would have their status changed from disabled to enabled after installation of a new version of Firefox. From version 22 of Firefox this will no longer happen, control of plugins has been moved from pluginreg.dat file to about:config.

Config name:	plugin.state
Default	Disabled: 0
Modified	Enabled: 1

HiDPI Scaling in Firefox

Config name:	layout.css.devPixelsPerPx
Default:	-1.0
Modified:	1.5

NOTE: 1.5 is an arbitrary figure, experimentation is fun.

User Interface Density

Hamburger icon --> Customise --> Density (bottom of screen) --> choose your poison.

Session Restore Frequency

Config name:	browser.sessionstore.interval
Default:	10000
Modified:	60000

NOTE: 1000 equals 1 second so 60000 equals 1 minute.

Zoom Limits Setting

The maximum increase in size can be altered:

Config name:	zoom.maxPercent
Default:	300 (percent - so modify to more than 300)
Modified:	500 (percent)

Likewise the decrease in size can be altered:

Config name:	zoom.minPercent
Default:	30 (percent - so you can modify to smaller or set the minimum size higher)
Modified:	60 (percent)