If you’re like most people, you probably have a few custom entries in your about:config file that you don’t want anyone else to see. This is especially true if you’re a web developer or use a different web browser than the ones your friends and family use. There are a few ways to remove these entries without having to remove the entire file or even change your settings. Here are three methods:

  1. Use an editor such as Notepad or Emacs.
  2. Use a command line tool such as sudo or cp -R .config/.configs/.org .
  3. Use the –disable-custom-browser option to a web browser such as Chrome, Firefox, Safari, Opera, and IE.
  4. Edit the about:config file using an editor such as Notepad or Emacs. The first step is to identify the line that contains your custom entry. For example, if you have an entry for “browser” in about:config, then it would be found on line 5 of the file. To remove this entry from about:config, simply delete the string “browser” and replace it with “notbrowser”. Now your about:config will be cleanly updated without any custom entries!
  5. Use sudo or cp -R .config/.configs/.org to copy the entire contents of your about:config file over to another location (for example, /usr/local/etc). Then use notepad or Emacs to edit this new location and remove any custom entries you may have added there.3) Use the –disable-custom-browser option to a web browser such as Chrome, Firefox, Safari, Opera, and IE. This method is slightly more complicated but it works just like the first two methods described above - all you need do is replace “browser” with “notbrowser” on lines 5 and 7 of about: config and your custom entries will be removed!

Note: It is highly recommended to keep a set of notes or listing of any modifications that you make to your about:config settings (default or custom entries). This is an extremely valuable asset if you need to undo changes at a later date.

The browser version used in our example is Firefox 3.5-beta99 and the custom added about:config entry is “nglayout.initialpaint.delay”.

Digging into about:config

To get started, type “about:config” (without the quote marks) into the address bar and hit “Enter”. With the new beta version this is the message that you will see once you have hit “Enter” (unless you have previously deactivated this window by deselecting “Show this warning next time”). Click on “I’ll be careful, I promise!”.

Once you have clicked through, your browser window is going to look like this.

Since we know the exact custom about:config entry we are looking for, type or paste “nglayout.initialpaint.delay” (without the quote marks) into the “Filter” address bar (you do not need to hit “Enter” in order for the entry to display). And there is the entry we are looking for sorted out by itself.

Now we can make the tweak that we need to remove this custom entry from Firefox’s about:config entry set. Right click on the individual about:config entry line and select “Reset”.

Once you have clicked “Reset”, notice that the about:config entry is no longer in bold print, has been changed from a “user set integer” to a “default string”, and is now blank in the “Value” area.

At this point, you will need to restart your browser. Once you have restarted, it is time to verify that the custom about:config has been removed. Repeat the process of opening up the about:config window as listed as above and once again enter the name of the custom entry into the “Filter” address bar.

As you can see, the entry no longer exists…you have effectively erased it from your browser!

Conclusion

If you like experimenting with custom about:config entries in order to increase your browser’s performance, this tweak can be extremely useful to undo a change that may not be working very well for you. Have fun tweaking your browser!