Useful toot, but please check why it's causing problem at homepage https://www.seb.lv/ - second line menus don't work! Error: Permission denied to access property "apply"!

I've tried using this add-on in Firefox (the most recent two versions), and it interferes with web page operation. Example: on Amazon.com, it prevented me from opening Wishlist or Customer Images links. The URL changed, but nothing happened. I isolated the offending add-on to this one by enabling / disabling. This problem occurred in various other ways on websites using similar code for certain features.