With version 38, Mozilla is going enable a new Preferences feature by default. These new Preferences will be shown inside a tab, like a regular web page. Users who are not happy with the new appearance of Preferences in Firefox 38 can follow this tutorial to disable it and restore the old Preferences dialog.
At the moment of this writing, Firefox 38 is still in beta channel but already includes the new Preferences by default. 
The settings inside it are categorized by rows on the left. Its design reminds me of the add-ons manager we have in Firefox. Probably Mozilla implemented settings in this way to get a consistent look across all operating systems and devices.
If you decide to restore the old Preferences dialog in Firefox 38, you need to do the following:
- Run Firefox 38, open a new tab and enter the following text in the address bar:
about:config
Confirm that you will be careful if a warning message appears for you.
- Enter the following text in the filter box:
browser.preferences.inContent
- You will see the parameter browser.preferences.inContent. Set it to false:
- Now open Preferences. You will see the old dialog:
Tell us, which Preferences UI do you like? Do you prefer the old tabbed dialog or will you use the new in-tab UI? (via Techdows).
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There was, and is, nothing at all wrong with the old tabbed dialog. There is no reason to change something that is familiar, intuitive, and functional. Change for the sake of change creates an unnecessary learning curve and is, therefore, stupid.
Thanks. The new preferences doesn’t remember which tab I lasted used. Its like a step back compared to the old.
The lack of memory of the previously selected options page is probably my biggest gripe about the Ff 38 options settings. Glad I found this article (via Google search, for the record).
I liked the old style better. The new style requires me to scroll, since it makes such bad use of screen screen, with no apparent concern for the size of the screen. I’m tired of changes in my browser and operating system and don’t want them to ever change again aside from security updates and essential changes such as dealing with new file formats. Feels like half my time at the computer is undoing changes and fixing problems caused by changes.
One of the (many) reasons I still prefer Firefox to Chrome has been a tabbed-dialog preferences UI model. Perhaps they’re doing this to reclaim some users that switched to Chrome as their default. So long as Firefox never takes away the ability to switch back to the dialog UI, I’ll be happy. I still refuse to have “tabs on top”; thank goodness for the Classic Theme Restorer add-on.
I didn’t have much choice but to revert to the old dialog box. For some reason, my mouse won’t work at all in the tabbed preferences window. It works just fine everywhere else, but not there.
Thanks for the tip! I still like Firefox and have it as my main browser, but I’m tired of useless changes for the sake of make the browser look “cool” instead of make real improvements.
I have my browser customized with dark background colors and light/white foreground colors, and the new preferences dialogs don’t care about colors preferences. So it was painful for eyes when opened preferences and noticed the changes (all text was unreadable!).
Now the only problem is with error dialogs (like the server error pages when a website is down or don’t exists). In this cases the page loads with both background and text colors as white, so it makes it unreadable until selecting text with mouse. Do you know if there are more variables at about:config to set this new change to false with error pages, as well as with customize dialogs?
Thanks again! :)