I'm closing this to reduce scope since it's likely we won't actually need this feature, and usage in the current page is less than 0.4% on all channels.

99% of the people who use this screen are of the sorts that might have telemetry disabled

It's no longer possible to get an overview of modified prefs.

Re-closing as bug 1502867 could help.

Everybody ending up googling for "about:config sort" you can (for now) enter "chrome://global/content/config.xul" instead of "about:config" to get back the old sortable layout. Then you can sort for the "status" column to only see the changed (non-default) values.

Is there a way to make about:config use "chrome://global/content/config.xul" instead of the new implementation?

Is there a plan to remove "chrome://global/content/config.xul"?

The Firefox Desktop team has now stopped maintaining and fixing bugs in the old "about:config" page. I believe Thunderbird may still be using the old code, so for the time being the page will probably continue to work while the code is maintained by the developers working on it.

At some point, the removal of the obsolete XUL technology will make the old page unusable, and we'll stop distributing it in Firefox. This obsolescence is the reason why we created the new version based on modern HTML. The removal is tracked by bug 1524782, but I expect it to happen based on opportunity and not at a specific planned time.

There is no way to point the "about:config" URL to the old page. There is an impressive amount of work involved in developing and maintaining such an apparently simple page, involving several people for several months, and maintaining multiple versions would be a waste of people's time.

It is disappointing to hear that it will go away, but thanks for the info anyway.

To everyone who like me found this bug via Google, will dearly miss the old, sortable about:config and had the issue that chrome://global/content/config.xul didn't work any more. Here is the solution:

chrome://global/content/config.xhtml

They changed the file extension. I hope that helps you until they unfortunately kill it off.

Oh and btw: Trusting blindly your "telemetry" is bad because your most faithful user base has it deactivated. The so called "power users" use Firefox for exactly those features that others browser are lacking. Trying to fish for the chrome user base is futile and doing so is alienating your most faithful users.

PS: If you want to delete my post because of my "political" statement, please have the decency to just delete the political parts and keep the information about the changed file extension. Thank you.