I am a huge fan and long time user of another browser add on called Social Fixer. I would be lost without this extension. Allows me to hide many elements and features on Facebook than FB Purity does also.
The authors of these great programs are up against frequent code changes by the Facebook programmers. It is an ongoing battle.
At any rate, check out Social Fixer… Matt Kruse is the only person who created and frequently updates this great program.