How to Tweak Firefox’s Advanced Settings with “about config”?

Firefox is a highly customizable browser. However not everything in Firefox can be customized from the Options Menu. If you are a very avid user of Firefox, then you might have already installed several extensions or add-ons to it in order to change it’s appearance or some of it’s default behaviors. Most of the time these add-ons make changes to Firefox’s user preferences which are otherwise accessible from the about config page.

What is ‘about config’?
The about config is a place where you can view and make changes to all the settings of Firefox. You need to know the implications well before modifying the entries in about config.

Many tweaks such as opening tabs in background, changing the width of displayed tabs, enabling auto completion in address bar, default behavior of your mouse clicks and scrolling etc can be done via the about config without installing any add-ons.

How to open and make changes to ‘about config’?
1. Type about:config in address (location) bar and press Enter.
2. You will see a warning as shown in the below image. Click on the “I’ll be careful, I promise!”
button.

3. This will open up the about:config window. Here you can add, modify or reset the preferences.

Let us take a look at a simple example of modifying a preference.
 

About Config Tweak Example: Making Firefox open Search Results in a New Tab
When we type a search term in the Search bar and press Enter the search results are shown in the current tab. You can make Firefox open the search results in a new tab by using ALT+Enter keys or by clicking on the Search icon in the Search bar with the scroll wheel of your mouse. However this works only for that particular search. If you want to have this behavior as default in Firefox then you will have to change the user preference browser.search.openintab. This is a boolean setting which means that it toggles between true and false.

1. Open About:config in Firefox (as described above)

2. Find browser.search.openintab by entering it in the filter box. (You can find many
other related settings from the filter box. For e.g., in order to find all search related settings,
type in browser.search)

3. Double Click on this preference to change it’s value to true.

From now on you will get all your search results in a new tab whenever you press Enter in the search box. However, pressing ALT+Enter makes the search results appear in the current tab itself!