The options Page doesn't open (a "Loading..." message shows up forever). Tried several gestures and none did anything, so I guess it doesn't work on Firefox 52 ESR (which I'm stuck to, at work, a Windows Vista machine I cannot upgrade).

I also discovered that the add-on is HUGE. It's 639kB in size, being 397kB used by TWO images, one with a huge Chinese advertisement (offering whatever for 99-whatevers) and another with some unrelated spaceship drawing... Oh, and there is an RSS icon (what for?!), 18kB in size... I don't know if this add-on works on other versions of Firefox, it's so recklessly assembled together that I don't care any more...