And while Mozilla recently announced that they would put an end to third party add-on installations, they made it clear that protection from plugin installations nor preference changes will be included in upcoming versions of the web browser.

Preferences Monitor is a new Firefox add-on that monitors the settings and preferences of the web browser. In particular, it monitors changes made by Firefox, by extensions that modify they own preferences and by extensions that modify other Firefox preferences.

All preferences modifications are logged in the Error Console of the browser. You can open it with the keyboard shortcut Ctrl-Shift-J or Firefox > Web Developer > Error Console.

Changes made by extensions to private Firefox preferences are furthermore displayed in the notification bar at the top of the web browser. The notification includes a More Info button linking to the changes in the Error Console.

The extension displays both the old value of the property and the new value in the error log. Users can use the information to restore the old values easily if the need should arise.

Monitoring Firefox preference changes makes sense. The developer should consider improving the extension further by adding better reporting options, the ability to restore preferences directly and options to block certain preferences from being changed in first place.

Firefox users can download and install Preferences Monitor from the official Mozilla Firefox add-on repository. (via)

Modified parameters in about:config are highlighted in bold, but there is not a way to display only those preferences in the web browser. And even if you could do that, you still would not see all modified preferences in a single interface.

Good news though that there is a way to display all modified preferences in Firefox. This is done via the about:support troubleshooting information page.

Simply enter about:support in the Firefox address bar and hit the enter key. This should open the Troubleshooting Information page in the browser.

If you scroll down a bit there you’ll find the modified preferences listing there.

Here you find a listing of all preferences that have been modified in this version of Firefox. Please note that the modifications are user specific, and that different modified preferences will be shown for those user accounts (unless they are duplicates).

Each modified preference relates directly to an entry in Firefox’s about:config listing of preferences. Entries are not linked and it is not possible to change their value from the troubleshooting page. Best practice therefor is to have both the about:support and about:config pages open in windows next to each other. This way you could copy the preference’s name into the about:config filter to find the preferences there easily.

The modified preferences listing can be used to troubleshoot issues in the browser. The information can be copied and pasted into another document as part of the troubleshooting process, for instance for documentation purposes. (via)

ECleaner is not the first Firefox extension to delete old extension preferences in the Firefox browser. Firefox Prefs.js Cleaner and Firefox Preferences Cleaner have been two extensions with similar options.

Ncleaner in its current state displays a list of preferences in its interface. The extension tries to sort the preferences by extension or type to make identification as easy as possible.

All you need to do now is to identify those preferences that are no longer used in the browser. This can be really easy if you know the names of extensions that you have used in the past, and not so good if you are not sure about a listed extension or preference.

The issue here is that the extension does not check if a parameter is still used by the browser or an extension, or if it has been a preference of an uninstalled extension

The list opens with a click on the Options button in the Firefox add-on listing. This listing can aid the user in the decision making process. I for one would backup the prefs.js file first in the user folder before making any changes, just to be on the safe side here.

It might also be a good idea to only delete those preferences that you are 100% sure about that they have been used by extensions that are no longer installed in the browser.

Firefox users can dwonload eCleaner from the official Mozilla Firefox add-on repository.

The new Firefox add-on Preferences Cleaner seems to offer that functionality. The description is unfortunately in Russian, the translation gives hints about the functionality.

The extension adds an entry to the Tools menu of the browser. A click on the entry Clear Preferences there opens the window that you see on the screenshot above.

The window lists all installed Firefox add-ons, with an option to hide disabled add-ons. You can enable the deletion of preferences of specific extensions by default. If you do, the preferences are automatically removed from the Firefox configuration when the extension is uninstalled.

You can alternatively switch to the uninstalled extensions tabs which lists uninstalled add-ons and their remaining preferences.

This tab can be used to remove those preferences from the Firefox configuration. Keep in mind that only preferences set in the Firefox add-on’s installation files will be listed here. Configuration entries that have been added after add-on installation are not listed here.

For that, you need to click on the Loose button at the top. This opens a new screen that lists all custom preferences. Those do not have to be obsolete, and some may be needed to run the web browser. You can use the listing to identify preferences of uninstalled add-ons, and delete those preferences.

Preferences are deleted by highlighting one or multiple of them in the window and pressing the Delete key on the keyboard or clicking on the delete button in the program interface.

Preferences can be exported and imported, which can act as a backup. It is suggested to export preferences before you delete them to be able to restore them at a later point, for instance if the deletion rendered an installed add-on useless.

Preferences Cleaner for Firefox is a step in the right direction. The add-on could use a help file or at least tooltips to guide first time users and provide them with explanations when needed.

The add-on is however a must have add-on for Firefox users who often install and uninstall add-ons in the web browser.

The brand new Firefox add-on What’s That Preference closes this gap, by linking preferences of the web browser to entries at Mozillazine. It should be noted that the site does not cover all Firefox preferences, but for those that it does, it is usually the best source of information.

The extension adds an entry to the right-click context menu in the advanced Firefox configuration listing. You can open that page by entering about:config in the Firefox address bar to load the preference listing. First time users need to confirm the warning message before they can start making changes to the configuration.

Just right-click a preference and select the MozillaZine reference link that is displayed in the context menu. This opens the corresponding MozillaZine page in a new tab in Firefox.

You find detailed information about the selected parameter if the entry exists on MozillaZine, which it does for most of the standard preferences available under about:config.

What’s That Preference is a handy extension for users who make changes regularly to the advanced preferences of the web browser. It can save lots of web searching for preference definitions.

The extension is available for all versions of Firefox 4 and newer. It can be directly installed over at the official Mozilla Firefox add-on repository.

Firefox ignores the custom preferences that have been created by the now uninstalled add-on, which means that they remain in the prefs.js file in the profile folder.

The number of dead preferences in the configuration file grows over time, practically with every uninstalled add-on, even though it has to be mentioned that some add-ons do not write to the preferences file.

Why is a large prefs.js file size a problem? Three different reasons come to mind. Firefox needs more time to load a larger prefs.js file. This means an extended browser startup and shutdown. The second is privacy related. It is theoretically possible to extract valuable information out of some preferences, e.g. installed add-ons or add-on specific settings that spill more information. Lastly, it may result in incompatibilities, although that is usually not the case.

In Firefox Spring Cleaning we mentioned how to clean the prefs.js file manually, to remove obsolete entries from it. This manual process reduced the file size of the prefs.js file on our test system to half its original value. Results vary highly however, depending on the number of add-ons installed, and how they make use of the preferences file. One commenter mentioned that the prefs.js file was 7 Megabytes on the computer, which is huge, and not the norm. The size normally ranges between 20 to 200 Kilobytes.

Manually cleaning the preferences has its advantages. It gives the user control over the process, but can result in errors as well.

The portable software FFPCleaner, Firefox Prefs.js Cleaner, semi-automates the process. The application displays a file browser on startup to locate a Firefox profile folder on the computer system. It supports therefor both installed and portable versions of the Internet browser.

The prefs.js file is then automatically loaded in the app. A word of warning: While it seems that the add-on filters out some core Firefox preferences in the file, it fails to locate all of them. The data displayed is made up of core preferences, existing add-on preferences and obsolete preferences of add-ons that are not installed anymore.

firefox profile cleaner

The data is sorted into names, and their row count, which makes identification a lot easier. It is still required to double-check the preferences to make sure that only obsolete data is removed.

FFPCleaner can create a backup of the prefs.js file before removing selected entries from the file. This is highly recommended to avoid the deletion of important information.

Placing a checkmark into the Delete box of a row in the program ensures that the preferences linked to the row get deleted when the Remove Selected button is clicked on.

Several features are currently missing in the program that would make it invaluable. It would for instance be handy to click on a preference to display all of it’s preferences in prefs.js. Some extensions, like Greasemonkey, store script preferences as well. While Greasemonkey may still be installed, some userscripts may not, which means that it would make sense to only clean the entries of those scrips, and not the whole Greasemonkey entries. Currently, those have to be ignored in the program.

Furthermore, all native Firefox preferences should be filtered out automatically, to avoid deleting those. While they are probably regenerated on the next browser startup, it might mean tweaking them again in Firefox to retain the desired values. Filters should also be applied to Firefox add-ons that are still installed in the browser, with options to display them if necessary.

Finally, statistics about the removed entries would be a nice addition to the program. The application could display the size of the file before and after the operation, so that the benefits of using it become visible.

The Firefox Prefs.js Cleaner is handy program for users who want to clean their Firefox preferences file, without having to do it manually. Download available at the developer website. The software was tested on a Windows 7 64-bit test system, no problems were encountered.

The Mozilla developers should consider improving the uninstallation of add-ons, so that obsolete preferences get deleted during the uninstallation. Resolving that core issue would make more sense than adding more eye candy to the browser.

Most basic preferences, like changing the homepage, switching scripting languages on or off, configuring web proxy servers, and changing privacy and history features are accessible from the options menu as well.

Both ways to change parameters have the disadvantage that it takes time to change the settings. That’s fine if ithey are one-time or once-a-month changes, not so if the changes are made on a daily or even hourly basis.

Prefswitch displays several new links in the Firefox status bar upon installation. Among them an options and profile manager, and several basic configuration switches including changing default cookie, JavaScript, frames and images behavior.

A left-click on an icon displays the available choices. Most of the time the options are to restrict, block or default the parameter.

prefswitch

The most interesting ability of the add-on however is the option to create new preference switches. This is done by right-clicking the status bar while the mouse hovers over an add-on item, and the selection of Manage Switches.

All preconfigured switches are displayed in the menu, of which some are not included by default in the status bar.

firefox preferences

A new switch is created by clicking the New Switch button and entering a name. The initial is a shortcut that is displayed in the statusbar, it can be descriptive but does not have to be. States define the different states of the parameters, one basic example would be to configure proxy usage, set the default state to no proxy, the state Europe to a European proxy and the state US to a proxy server from the United States.

Basic Example

The preferences that change these parameters need to be known. It is helpful to open about:config in the background to quickly find and copy preferences into the required fields.

Here is a quick example. Let us assume we want a new switch to quickly switch between offline and online browsing modes. The boolean parameter in about:config is browser.offline. If it is set to true the browser is in offline browsing mode, false means the browser is in online mode.

Click on New Switch and add a name for the new switch, e.g. Offline Browsing. Put O in the Initial field.

Click on new state and name it default. Click in the Preferences field and paste browser.offline in it.
Change the value to false, as the default state of this preference is set to false, meaning the browser will not start in offline mode but in online mode. Click the add button in the end.

Create a second state and name it offline. Perform the same operation as above, the only difference is the value of the parameter which needs to be set to true.

You should have two states configured now, both with the preference browser.offline, one with the Boolean value true, the other false.

offline browsing

A click on the Accept button saves the changes and places the initial in the Firefox status bar.

config parameters

The parameters that are shown in the status bar are configured in the right-click Show / Hide menu. All custom parameters are automatically added to the status bar.

The above example was basic in nature. It is possible to add multiple preferences to each state, which makes it in theory possible to perform several configuration changes with a click on the status bar. Some of the preset states show this behavior.

Another interesting option is support for profiles. Profiles can be used to change the states of multiple switches at once. Prefswitch again offers the option to create custom profiles. All custom switches that are added to the program are also shown in the profiles window.

manage profiles

Prefswitch can be a very handy add-on, especially for advanced Firefox users who regularly change settings in the web browser.

This could also be helpful if you regularly install and uninstall Firefox on the same computer or if you want to merge profiles. The OPIE – Ordered Preference Import/Export – extension provides the user with means to import and export preferences from selected Firefox extensions. Some or all of the extensions can be selected during export and they can be saved in a single file or separate files for each extension. The latter is useful for merging profiles or sending preferences of specific extensions to another computer.

The import of preferences works pretty much the same way. The only difference is that a previously exported file is selected that is imported into Firefox. The results are shown in the same window.

The files are saved with the .prefs extension so that they are better recognizable. The benefit of using OPIE instead of a full Firefox backup extension like FEBE – Firefox Environment Backup Extension – is that OPIE can selectively export and import preferences while all other extensions that backup Firefox settings can only import and export all settings.