The WebExtensions technology that uses the same extension API supported by Google Chrome, Opera, and Microsoft Edge web browser. So the API is also fully compatible with multiprocess Firefox (is called Electrolysis, sometimes abbreviated to e10s). The Electrolysis split Firefox into a UI process and a content process. The splitting UI from content means that when a web page is devouring your computer’s processor, your tabs and buttons and menus won’t lock up too.

Firefox WebExtensions
If you want to install the Turn Off the Lights Firefox extension in your Firefox web browser. And you see this error message “Not available for Firefox 48.0”. Then this is the important notes on what web browser you can use this useful Turn Off the Lights Firefox extension version.
Version 3.2.0.12 – that is the latest XUL version for Firefox version 48
Version 3.2.0.15 – that use the WebExtensions version for Firefox version 49 and higher
You can download both Firefox extension version on the Turn Off the Lights Firefox extension history page. And for the latest version go to the official Turn Off the Lights download page. So where you can enjoy the latest and new innovated way to get the best video and web experience.
Did you find technical, factual or grammatical errors on the Turn Off the Lights website?
You can report a technical problem using the Turn Off the Lights online technical error feedback form.