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.

That’s inconsistent and something that has bothered me for quote some time. See, I use the Multi Links add-on for Firefox to open multiple links at once in the browser. These often open at the end of the tab row which is not how I want it to be.

Lets take a look at the available options in Firefox. The Tools > Options > Tab menu offers no help. It offers general tab related settings but no configuration option to change the way new tabs are opened.

The only other built-in option is to enter about:config in the Firefox address bar, hit enter, confirm the notification if it appears and filter for the term “browser.tabs”. Please note that this has only been tested under Firefox 4, the parameters may be different under Firefox 3.6.

Locate the browser.tabs.insertRelatedAfterCurrent parameter. It is set to True which is the default behavior. True basically means that related tabs will be opened to the right of the current tab. Firefox users who want to change that behavior can double-click the parameter to set the value from true to false.

False means that all tabs are opened at the end of the tab row.

But what about users who want new tabs to always open direct next to the active tab?

Those users need to install an add-on, like the restartless Always Right add-on. The Firefox extension configures the browser to open all tabs, regardless of their relation to the active tab, to the direct right of the active tab.

There you have it. Users who want all tabs to open at the end of the tabbar need to make the change in the about:config dialog, users who prefer that all tabs open directly next to the active tab need to use an extension for that.

What’s left to say? How do you like your tabs?

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.

The second action is the auto-complete feature that kicks in under certain circumstances only be default. Entering Mozilla will load the mozilla.com website automatically because that is the best match in the Google search engine for that name. A search for www.mozilla on the other hand will be auto-completed by Firefox. The browser will append the .com suffix to the query and load the same website.

Not everyone is living in the United States and some users might prefer a country domain extension instead of the default .com suffix. This option can be changed in the Firefox preferences. Entering about:config in the Firefox address bar will load the preferences.

Filtering for the term fixup will show the four parameters on the screenshot above. A user can change the default prefix and suffix to something else by double-clicking the entries or disable the auto-complete feature completely by setting the browser.fixup.alternate.enabled parameter to false.

To give you a practical example: If you visit https://www.paypal.com/ you notice a large green bar in the favicon area that is displaying the name of the owner of the website. A visit of https://www.amazon.com/ on the other hand is displaying a smaller blue bar around the favicon. Both are secure websites but one is dominant while the other is barely visible.

This can be changed in Firefox 3 so that the url of the website is displayed in the favicon are as well. To do that type in about:config in the Firefox 3 location bar and filter for the term browser.identity.ssl_domain_display. You can change that term to the following values:

• 0 – the default value.
• 1 – the top level domain is also painted in blue. e.g. ghacks.net
• 2 – all of the domain is painted in blue, e.g. www.ghacks.net

I set mine to the value 2 so that the complete domain name is shown in the favicon area.

Configuration Mania is a Firefox add-on that displays many of those “deeper” settings in a menu that resembles the Firefox options menu. Users can access five main tabs, like Browser or Security, which lead to several subtabs that provide access to the settings.

Let me give you an example that helped me actually. Clicking on the Browser tab opens a menu with several like User Agent, Location Bar and Download. A click on Download revealed the option to disable the alert that you receive when a download finishes. I would have a hard time finding that option in the about:config settings.

Users who would like to keep the alert can chance the interval in that it is shown and even increase or decrease the speed of the animation. You can find dozens of such helpful settings in Configuration Mania.

I should probably start with some basic information on how you edit the Firefox configuration at all. This is actually pretty simple: Enter about:config in the address bar and hit enter. A large preferences list should appear. Every option has a preference name, a status, a type and a value.We are using the name to find the option in the large list. Status defines if it is still the default value or has been edited by the user, type defines which values are accepted in the value field. For boolean it would be true or false, integer a number and so on. To filter the list enter part of the name into the Filter text field, the results get updated on the fly. On to the tweaks..

Change location of bookmarks file

• key: browser.bookmarks.file
• default: not existing, create new String by right-clicking and entering the above key
• value: path to bookmark.html, for instance e:\bookmark.html

You might want to change this if you want to use a removable drive to store your bookmarks for instance.

Middlemouse Paste

• key: middlemouse.paste
• default: false
• change to: true

Setting this option to true makes it possible to paste text into any text field in Firefox.

Hide Go Button

• key:browser.urlbar.hideGoButton
• default:false
• change to:true

If you set this value to true the Go button will be removed giving you more space in that bar. No one uses the go button anyway, just hit enter, this has the same effect.

Click Selects all in url bar

• key:browser.urlbar.clickSelectsAll
• default:true
• change to:false

This is useful if you often copy only part of the url. The default behavior selects the complete url first if you click into the url bar and you have to click and select again to copy part of the url only.

Open Search Results in a new Tab

• key:browser.search.openintab
• default:false
• change to: true

Opens the search results always in a new tab instead of the currently active tab.

Spellcheck for textareas

• key:layout.spellcheckDefault
• default:1
• change to: 2

This activates the spell check for textareas and input fields as well.

Autofill in url bar

• key:browser.urlbar.autoFill
• default:false
• change to:true

Known urls are automatically completed while entering them.

Disable extension compatibility check

• key:extensions.checkCompatibility
• default: not existing, create new Boolean with the above name
• value: false

Setting this value to false means that Firefox will not check installed extensions for compatibility. Great during updates, could lead to problems with incompatible extensions though.