Have you ever added a custom about:config entry to your Firefox browser and then wished that you could remove it? Now you can with a simple reset tweak that focuses on singular entries.

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!


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!

Akemi Iwaya
Akemi Iwaya has been part of the How-To Geek/LifeSavvy Media team since 2009. She has previously written under the pen name "Asian Angel" and was a Lifehacker intern before joining How-To Geek/LifeSavvy Media. She has been quoted as an authoritative source by ZDNet Worldwide.
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