There's no question that Mozilla Firefox has become the darling of the web browser world. A quick peak at our browser stats shows its popularity is growing. As interest in the product has grown, so have the questions regarding its feature. One popular question concerns how to set the preferences. (Includes flash tutorial)

Often, when you think of program settings for a Windows program, your mind conjures up the Windows registry, which is the main settings repository. In contrast, Firefox offers several ways to tweak preferences aside from the Options panel. One quick way to access these settings is to type about:config in the browser address bar.

After typing this text string, you're presented with a long list of preferences. Each preference defines a specific Firefox behavior. The length of the list varies based on your plug-ins and extensions. The list comprises any item that can be set using Tools|Options and many others. In addition, you can add preferences. You might think of this list as a superset of Firefox options.

The list displays four columns: Preference Name, Status, Type and Value. You can click a column to resort the list. Sortable columns are a nice feature because the Find in This Page feature doesn't appear to work with this list. At the top of the vertical scrollbar, you should see a small table icon that allows you to show or hide columns.

You can guess the meaning of some preferences by their name. As example, the highlighted line in the picture above, browser.startup.homepage, indicates which page is your home page. Once you add a preference or change the default value, the line displays in bold text.

Most of the changes people want to make can be done using Firefox's Tools menu and then selecting Options. Any change you make through Options shows in this list. However, there may be certain tweaks you want to perform that are not covered by the Options dialog. In those instances, you can modify or create the Preference using about:config. The hardest part is finding out what each preference controls.

Although many of the 1100 preferences have been documented, many are not verified. The best way to find out about a specific preference is to check http://preferential.mozdev.org/preferences.html. If you see an item ending with a question mark, that's your indication the author is looking for confirmation. Initially, we suggest you avoid playing with these preferences.

Chances are if you scan this list, you'll see items you wish to change. As example, when we scrolled the Mozdev list, we found an entry that indicates we can set our mouse scroll wheel and ALT key to move through session history.

To make this change we would do the following:

1. Open Firefox

2. In the address bar, type about:config and press the Enter key.

3. Click the Preference Name column to resort by that column.

4. Scroll down till you find the preference labeled mousewheel.withaltkey.action

5. Right-click the entry and select Modify from the pop-up menu.

6. In the Enter integer value box, type the number that matches the behavior you wish. If you wish the Alt key and mouse wheel combination to move through history, enter 2 and so on.

7. Click OK.

Some settings need you to close and restart Firefox before the change takes effect. We would also suggest that you only change one item at a time. If you change multiple items and then something doesn't work correctly, you'll have a harder time diagnosing which change may have contributed to the problem. If you run into a problem, you can usually use the Reset function. This menu option appears when you right-click on values you've changed.

For power users, there is a very good and long forum thread at Mozillazine. The topic has several hundred posts with people volunteering information and recommending settings. As with any setting change, we recommend that you write down your changes. What works for one user, may not work as you expected. All the same, it's nice to have this control.

Firefox Screencast

• 3-Minute Tutorial on Adding Memory Tweaks

Additional Firefox Resources

• Mozillazine Tweaks Forum Discussion
• Mozdev Org Listing of Preferences (Long List)
• Mozillazine Listing of Preferences (Short List)
• Mozillazine Article on Changing Preferences