You save the extension to your pc then right click on it and “open with” notepad. You then change the version number if the creator of the app did not come up with an update. Now they are saying it won’t work.
Firefox has lost 3.3 percentage points of user share in the past 12 months, representing a decline of 16% from its April 2013 standing.
So they alienate the remaining customers with a design that people had been complaining about when it was in beta form. Hmmm... sounds like they hired people from Microsoft 8 build team.
At least some one is trying to fix it. See the screenshot at the bottom of the article.
“The Classic Theme Restorer add-on will return some, but not all, of Firefox 29’s UI elements to their previous positions, including the main menu that had lived on the left side of the windows since 2011.”