The core audience on the other hand is comprised of advanced users who know that about:config exists, and know how to use it properly.

Probably the biggest drawback, besides the obvious lack of information about each parameter, is the user interface itself. It basically consists of a large unsorted table with hundreds of different entries.

Gui:config for Firefox offers a solution for the two drawbacks. It basically turns the about:config list of parameters into a user interface that resembles the Firefox options menu.

You can access the menu via the Firefox > Tools menu or by placing its icon into one of the toolbars of the Internet browser.

It will take some time to browse through all the options offered in that menu. The developer has divided settings into the two tabs accessibility and browser.

Accessibility deals with mouse behavior, the address bar, websites and other settings that are accessible to the user in the browser. The Browser configuration menu handles under-the-hood changes mostly.

Lets take a closer look at the available options:

Mouse Behavior – Mouse Click

• Load clipboard as url
• Paste text from clipboard
• Select content on mouse click
• Select content on double click

Mouse Behavior – Vertical Mouse Scrolling, Horizontal Mouse Scrolling

• Defines scrolling when no key is pressed and when the Shift, Alt or Ctrl key is pressed.

Awesombar

• Restrict to typed addresses
• Restrict to history
• Restrict to bookmarks
• Restrict to tags
• Search in title
• Search in url
• Maximum number of search results

Websites

• Find as you type: Case sensitive, not-case sensitive, timeout
• Auto-fill login form fields, tab focus elements, backspace behavior, spell checking

Session Restore

• Enable session restore
• Maximum number of restorable tabs, windows and concurrent tabs
• Store extra session data
• Restore sessions after crash

Misc

• Urlbar: Inline Autocomplete, use alternate address, insert at the beginning, at the end.
• Instant apply
• Show popup blocker icon in the status bar
• Show dialog box when entering caret browsing
• Access key activates the element

Browser Cache

• Check browser cache frequency
• Use Disk Cache, set disk cache
• Store HTTP / SSL content in cache
• Use Memory Cache, set memory cache
• Maximum number of pages in memory

Websites

• Enable Location-Aware Browsing
• Enable the HTML5 parser
• Enable SVG animations
• Enable WebGL
• Enable Direct2D
• Enable DirectWrite
• Enable 3D video
• Download fonts embedded in the website

Extensions

• Enable extension compatibility checking
• Always unpack extensions
• Maximum number of search results for the get add-ons pane

Most options are self-explanatory, while some, like instant apply, require research on part of the user to find out what they are about. That’s a issue that the developer needs to take into consideration. It could easily be fixed with tooltips that explain a setting on mouse over.

Gui:Config is a handy replacement for the about:config dialog in Firefox. I cannot really say if it contains all settings of that dialog, or only select ones. What I know for sure is that the add-on is not displaying extension preferences in its interface. Firefox users can download and install Gui:Config from the official Mozilla Firefox add-on repository.

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?

What you need

First, you will need a working Firefox browser. That is simple as nearly every distribution ships with Firefox. Next you will need to install the application apturl. To install this you can either find it from within Synaptic (NOTE: You will not find this within the Ubuntu Software Center) or you can install it from the command line. Let’s install from the command line:

1. Open up a terminal window.
2. Issue the command sudo apt-get install apturl.
3. Type your sudo password and hit Enter.
4. Accept any necessary dependencies.
5. Let the installation complete.

Now you are ready for a little Firefox configuration magic.

Configuring Firefox

Figure 1

If you’ve never worked with the about:config piece in Firefox, you are about to. The about:config page is a way to configure numerous hidden options in Firefox. This also allows you to create new configuration options. To get to this page open up Firefox and enter about:config in the address bar. You will be warned about the dangers of messing with this configuration and you will have to accept by clicking a button to continue on. Once within about:config you will see numerous strings that can be edited (see Figure 1).

Figure 2

What you have to do is create a new string. To do this right click anywhere on the page and select New > String. In the resulting window (see Figure 2) enter the following string:

network.protocol-handler.app.apt

Click OK and a new window will appear pre-filled with the string:

/usr/bin/apturl

OK that string to complete the new configuration. Now you have to add one more string. Right-click the about:config page, select New > String, and enter the following:

network.protocol-handler.app.apt+http

OK that and then OK the pre-filled in string for the value.

You are now ready to give it a try.

Installing

From Firefox, go to the site http://appnr.com and locate an application to install. You will notice, when you mouse over an application, an Install button will appear. Click on that application’s Install button and you will prompted for your sudo password. Once you authenticate to sudo the application will install without having to open an external application. Although the same things are going on in the background, it is just one step quicker than the standard GDebi install from within Firefox. And anything to make Linux easier is a plus.

The color settings are available as about:config parameters. Firefox users who want to change them need to enter about:config in the address bar and enter browser.display in the filter on top. This displays the relevant parameters in the listing.

Colors are represented by hex codes, a good overview of available colors and their hex codes is available at the Color Wheel website.

browser display form colors

browser.display.background_color defines the standard background color of all web forms that are displayed in the web browser. The default color is white (#ffffff)

browser.display.focus_background_color defines the background color for the active web form on Internet pages. The default value is green, the parameter is inactive however and needs to be activated by setting browser.display.use_focus_colors to true.

browser.display.focus_text_color defines the font color of the focused form, the form with the cursor in it.

Please note that the changes become active immediately. A good way to test them is to use the filter form on top of the about:config page.

browser display form colors

Changing web form colors in Firefox is a great option for users who are not happy with the standard colors, could be an option to make the colors easier on the eye or fit with the browser’s theme.

The file tends to grow over time, largely because entries from uninstalled extensions do not get deleted during uninstallation. Users who install and uninstall add-ons regularly might have a configuration file that is multiple times larger than the standard file.

That’s usually not a problem, a large file might prolong the startup of the web browser by a bit though. Privacy is another issue as some extensions record visits pages or specific rules for websites in the preferences.

The preferences are stored in the prefs.js file in the Firefox user profile directory. Use this guide if you do not know where it is located on your computer system.

It is recommended to create a backup before making any changes to the file to be able to restore it. Firefox needs to be closed before editing the prefs.js file as Firefox automatically saves the prefs.js file on close.

firefox configuration

Each parameter is stored in a separate line. Many extensions use user_pref(“extensions. in the beginning which makes identification easy, some however start directly with their own name.

The only viable option is to go through the configuration file and locate the extensions that are not installed anymore. That’s a tedious process but the only option at hand as there is no automation of the process available. A rule of thumb is to leave entries alone if they cannot be linked directly to extensions that have been uninstalled.

The size of the prefs.js file on the test system was 167 Kilobytes before spring cleaning. The first cleanup brought the file size down to 88 Kilobytes with room for more after some research.

Here are a few tips:

• It helps to have the names of the installed extensions and, if applicable, userscripts at hand.
• Parameters beginning with browser., dom., print. and .network refer to core browser preferences.
• If you are not sure about a specific setting do the following: Create a backup first, make the changes then and test Firefox to see if the functionality is still there. If you encounter errors restore the backup.

And this is how you delete about:config entries in Firefox.

It is really strange that no one ever build a Firefox preference cleaner that automatically removes old entries from the Firefox configuration file or that the developers have build that feature into the browser. How big is your file? Let us know in the comments.

When I first encountered this I immediately opened up about:config and searched everywhere for the entry that was causing this issue. No luck. Every possible entry “browser.online” entry was checked as “true”, but still the browser would start offline. Everywhere I looked it seemed it was set up properly…and this shouldn’t be a difficult issue. It was turning into a hair-losing situation. Eventually, however, I would figure out what was going on.

In many modern Linux distributions network management is controlled by the user-friendly NetworkManager utility. Sometimes there is a bit of a disconnect between Firefox and NetworkManager.? This doesn’t happen often (Most often this happens in Fedora.), but when it does happen it will make you feel like you have no idea what you are doing.

There are two ways to get around this. The first way is go hop on to Firefox, open the about:config window (you will most likely have to click the check box promising you’ll be careful using this configuration page), and do a search for the string:

toolkit.networkmanager.disble

By default this is set to false which means it is working in conjunction with NetworkManager to see if there is a connection. Set this string to true, restart Firefox, and you most likely will not have this problem again.

Figure 1

If you’d rather not monkey with the about: config page in Firefox you will have to change a setting in NetworkManager itself. You will find the NetworkManager entry in the Administration sub menu of the System menu. The entry is labeled “Network”. Click on the Network entry to open up the NetworkManager window (see Figure 1).

Select your method of connecting to the net and click the Edit button. A new window will appear that allows you to edit various aspects of this connection.

Figure 2

There is only one configuration you need to change here. If the box next to “Controlled by NetworkManager”is checked, uncheck it. If it is unchecked, check it. This will depend completely on how you manage your network connection.

Firefox by default uses NetworkManager to know if a connection has been made. If you use another tool for your network connection, and you have Firefox enabled to check NetworkManager, you will always start off line, because Firefox will think you have no connection.

My suggestion is that you first try the about:config entry. If that doesn’t work then give the NetworkManager approach a try. One way or another, you will be able to stop this insipid behavior.

Final Thoughts

The real culprit here, in my opinion, is that the developers of NetworkManager and the developers of Firefox can’t seem to agree on a standard. This, of course, is a problem that haunts Linux in a number of areas. In the case of this one issue, you now know a way around it.

The about:config address is a special location that allows you to change configuration options in Firefox. Most of these options aren’t every-day, end-user-friendly options. Instead these options can look a little overwhelming to the pedestrian. But to those that hold no fear of tweaking, about:config is your friend. In this article I will show you a few tweaks in about:config so you can get familiar with how this special configuration address is used.

When you first load about:config in your Firefox browser you will have to click an “I’ll Be Careful, I Promise” button that warns you what you are about to do can void your warranty. It’s okay, really, go ahead and push the button.

Once you push the button you will see entries like this:

accessibility.accesskeycausesactivation     default     boolean     true

The first entry is the Preference Name. Next is the Status, followed by the Type, and the Value. Each entry follows this same format.To change a value in an entry you only have to right click that entry and, depending up on the type of value, click the Toggle entry in the popup menu. If the value is, say, an integer a Modify entry will appear allowing you to modify the value of the entry.

Within the about:config there are various categories:

• Accessability
• Advanced
• Alerts
• Browser
• Config

Your about:config will show each entry arranged according to category. You will also find a very large amount of entries – don’t let that overwhelm you. You can also search your entries (thanks to the handy Filter.

So let’s take a look at a few about:config entries that will make a noticeable change in the speed of Firefox. These entries are:

• network.http.pipelining.
• network.http.proxy.pipelining
• network.http.pipelining.maxrequests

The fastest way to find this is to enter pipelining in the Filter.

Once you have found them you will do the following:

• Set network.http.pipelining to “true” by right clicking the entry and selecting Toggle.
• Set network.http.proxy.pipelining to “true” by right clicking the entry and selecting Toggle.
• Set network.http.pipelining.maxrequests to value like 50 by right clicking the entry, selecting Modify, entering the new value, and clicking OK.

Now let’s add a totally new entry to help speed up Firefox. Click anywhere and select New and then select integer. A small window will open asking for the name of the new entry. Enter nglayout.initialpaint.delay and give it a value of “0″ (no quotes) when prompted.

Firefox should now be noticeably faster.

Of course using about:config isn’t limited to speed. Browse through the listing of entries and you will notice that nearly every possible configuration option imaginable is there. Play around with familiar entries and see how far you can tweak Firefox. Just use caution, if you don’t know what an entry does make sure you look it up before you edit it. A good place to find information on each entry is the official Firefox about:config Entries database.

With Firefox 2, I use about:config to plug many of Firefox’s notorious memory leaks. The tips I used worked great and I never had any problems with my Firefox. A little while ago though someone posted an interesting question on Lifehacker that I hadn’t really thought about. What if you want to delete an about:config entry?

This is quite a practical question. Let’s say I misspell an entry as I’m typing it in. Obviously, I don’t want to keep these useless entries in my browser so I would get rid of them. The good part is that there’s a very simple way to delete redundant entries without causing any chaos with your browser.

To delete an entry, just right-click it and select Reset. Then, restart Firefox. If the value you chose was originally part of the browser, it will go back to its default value. If the value was added by you, it will be deleted.

I tried out this trick on my own version of Firefox with a few deliberately mistyped entries. It worked fine for me. This is a handy trick to know in case you ever make some unwanted adjustments to Firefox. What do you think of this tip? Do you know of any other way to delete about:config entries in Firefox? Let me know in the comments.

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.