After introducing the new one-click Searches UI and incontent preferences, Mozilla has removed the old Search UI and Windowed Preferences including their hidden about:config preferences browser.search.showOneOffButtons and browser.preferences.inContent in Firefox 43.
If you want them back, you can re-enable them with the help of an add-on, here is how.
Re-enable Old Search UI and Preferences Window in Firefox 43
1. Install Classic Theme Restorer add-on (latest version for this add-on on AMO is 1.4.1 at the time of writing this article on
2. Click on its ‘Options’ >General UI (1)
3. Check old Search (experimental) and open Options page (about:Preferences) in a window.
4. Click ‘OK’ to save the changes.
After making the above changes, Options page has not opened in a window for us, we’re expecting the CTR add-on developer to fix this in future versions, but the old Search UI has been enabled successfully.