Tweaks

Tweaks allow you to make changes to the Firefox browser behavior that can not be changed through the regular browser settings. The tweaks are classified into three categories: display, tabs and general. It is also important to note that not all tweaks will work on all versions of Firefox. Each tweak will include which versions of Firefox will support the tweak.

Disclaimer

The Firefox Extension Guru is an independent beta-tester and is not affiliated with Mozilla Corporation. While most of these tips, tricks, suggestions, etc. are relatively simple to do, there is still a risk of damaging your profile. Therefore these are recommended for advanced Firefox users and should be attempted at your own risk! Consider backing-up your profile or creating a new profile before attempting these tweaks.

Compatibility

Tweaks are tested for compatibility in Firefox 3.6 to the most recent Nightly versions.

Guide

Beginning November 15, 2025 we are doing away with the color-coded version compatibility. Instead we will list compatibility as a range (or single version). Examples:

  • Works with: Firefox 3.6 — only works with Firefox 3.6
  • Works with: Firefox 3.6+ — works with Firefox 3.6 and all newer
  • Works with: Firefox 4.0+ — works with Firefox 4.0 and all newer
  • *UNDER REVIEW**- Firefox x.x — tweak may not be yet working due to a dependent extension not yet compatible with this version of Firefox. More details will be in the Notes section.

How To Tweak

Most tweaks require the user to either change settings in their about:config settings or their userChrome.css file.

  • about:config - Some of the tweaks are done though the about:configinterface where users preferences can be viewed and modified. To access the about:config settings follow these simple steps:
    1. Open a new tab
    2. In the address bar type about:config
    3. Click the Go Button or press enter
    4. If this is your first time accessing this interface you will get a humors warning (loaded gun or void warranty). Click the I’ll be careful button to proceed.

    More information on the about:config entries can be found on mozillaZine about:config entries.

    • Interface - At the top of the windows is text filed labeled Filter. This allows you to only show entries that contain the word or words entered. The filter only applies to the Preference Name and Value fields. Entries in bold have been changed from the default and their status will show as user set. Every entry is one of three types:
      • Boolean - value is either True or False
      • Integer - value is numbers only
      • String - value is any character (text, numbers and special characters).
    • Changing Entries - To change and entry, either right-click on the entry and select Modify or double-click the entry. For Boolean entries doing so will toggle the value. Integer and String entries will produce a dialog box promoting for the new value. In the event the wrong entry is modified or the change produces undesirable results, right-click on the entry and select reset (note: this changes the value back to the default, not what it was prior to being modified.
  • userChrome.css -Some of the tweaks require modification to your userChrome.css file located in the chrome folder within your profile folder.
      • Modifying userChrome.css - Changes made to the userChrome.css file can NOT be undone once saved. Therefore before making any changes to the userChrome.css file make a back-up copy first.
      • IMPORTANT Close Firefox before saving changes made to your userChrome.css file.
      • WARNING!!! DO NOT REMOVE the line which starts with: @namespace

    This file should only be edited with a text-editor such as Notepad or Notepad++. It is NOT recommended using MS Word or similar Word Processor applications. For best results we recommend using the ChromeEdit Plus Extension. The extension will automatically locate your userChrome.css file and open it in an external editor.

Tweak Categories

The tweaks fall into one of these categories:

  • Add-ons Tweaks - Tweaks to help with Installing, managing and troubleshooting add-ons.
  • Display Tweaks - Changes to the overall Firefox display or how information is displayed within the browser.
  • General Tweaks - Changes to the overall behavior of the Firefox browser.
  • Tabs Tweaks - Changes to the behavior of the tabs and/or the tab bar.

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