Firefox

Firefox is Mozilla's solution to the web browser.

Aurora is the "unbranded" version of Mozilla's Firefox.

USE flags
The above list of USE flag is not comprehensive. Use (part of ) for a full list:

Emerge
To compile the source version of Firefox, issue:

Emerging the source version of Firefox can be a long process; a pre-compiled (binary) version does exist in the Portage tree, however users of the pre-built package should note the warning below. To emerge the Firefox binary, issue:

Disabling percent-encoding
Normally, URLs that are copied from the address bar get percent-encoded. This may cause an annoyance when certain non-Latin symbols (such as Cyrillic) get encoded, as they become unreadable to humans.

To disable percent-encoding when copying from the address bar, set the  option   to.

Special URLs
Firefox includes a few dozen special URLs that can be helpful in determining more information about various Firefox settings. These URLs can be entered into the Super Bar (via copy and paste) to view the special pages. A few of the more significant ones include:



A full list of special pages can be viewed on the Mozilla Zine wiki.

HTML 5 video support
Problem: Audio plays, but no video is visible.

Solution: Check, if flash block is enabled. Some websites like YouTube for example still require flash to play HTML 5 videos properly. (This is the situation on 2016-07-29 and may change in future.)

XDG integration
In order to make Firefox use XDG file associations set Content Type's Action to

To ensure Firefox is being used by other applications for handling HTTP and HTTPS links, run the following commands:

Running in sandbox
The Simple sandbox article explains why »Sandboxing Firefox is mandatory«.

Safer browsing with Add-ons
Firefox has a massive community behind it and a result many Add-ons have been created to aid with specific interests of users. Many users are concerned about their privacy (tracking, bubbling, targeting, etc) while web browsing. Installing Add-ons can aid in adding an extra level of privacy to their browsing.

The Add-on menu can be accessed by navigating the following menus:

Adblock
To block annoying ads use Adblock. Adblock does include an "acceptable ads" list (advertisers pay for that), so some advertisements are still displayed. For an Add-on that blocks all ads, see uBlock Origin.

Mozilla Add-ons page: https://addons.mozilla.org/en-US/firefox/addon/adblock-plus/

Homepage: https://adblockplus.org/en/

uBlock Origin
A new ad blocker with lower resource usage, using same lists as Adblock. Very versatile and configurable.

Mozilla Add-ons page: https://addons.mozilla.org/en/firefox/addon/ublock-origin/

GitHub: https://github.com/gorhill/uBlock

Wikipedia: https://en.wikipedia.org/wiki/UBlock

NoScript
NoScript blocks JavaScript that is normally enabled by default. It can keep users safe and speed up web browsing.

Mozilla Add-ons page: https://addons.mozilla.org/en-US/firefox/addon/noscript/

Homepage: https://noscript.net/

RefControl
RefControl is an extension that lets you control what gets sent as the HTTP Referer on a per-site basis.

Mozilla Add-ons page: https://addons.mozilla.org/en-US/firefox/addon/refcontrol/

Homepage: http://www.stardrifter.org/refcontrol/

Known problems:


 * LiveJournal: commenting post via OpenID leads to CAPTHA form, that didn’t work with “wrong” HTTP Referer (or maybe a problem in the commenting form itself).

uMatrix
Point and click to forbid/allow any class of requests made by your browser. Use it to block scripts, iframes, ads, Facebook, etc. uMatrix can also be used for spoofing HTTP referrer, spoofing User Agent strings, blocking hyperlink auditing and forcing strict HTTPS. Note, uMatrix can break many websites and most websites need configuration changes to work correctly.

Mozilla Add-ons page: https://addons.mozilla.org/en-US/firefox/addon/umatrix/

GitHub: https://github.com/gorhill/uMatrix

Middle mouse scroll (autoscroll)
Traditionally in Linux, the middle mouse button is used to paste the currently selected (highlighted) text into a text field. On Windows systems, the middle mouse button in Firefox is used for click-and-drag scrolling up and down the page. This functionality can be enabled in Firefox by opening  and setting the following value :



Middle click-and-drag scrolling should now be enabled.

Although not necessary, sometimes it is desirable to disable all other middle-click functionality within Firefox when using click-and-drap scrolling. Open  and set the following values to disable middle-click functionality:



Crashes
If Firefox crashes for no apparent reason every few minutes with an error message like  it might help to add the Firefox user(s) to the video group:

Mic permission request not appearing
It's known to affect Firefox 48.0. The streaming component full.duplex doesn't have Alsa support, (e.g.,, ). Firefox seems to be moving towards Pulseaudio and leaving Alsa for good.

The workaround to solve this issue is to deactivate full.duplex in Firefox, open Firefox go to about:config then look for media.navigator.audio.full.duplex and change it from 'true' to 'false'. Then, restart Firefox.

External resources

 * The official Firefox wiki (out-of-date)
 * Firefox on Mozilla's Forums
 * Firefox on Mozilla's Buglist
 * Change the interface language (LINGUAS)
 * Creating a new profile