@leocg The problem with this pop-up, and I think I will articulate this for the whole of community here -- the problem is that I did not click anything and yet the page content is covered up by browser chrome. This popup comes from the browser, not the content. And it covers up my page, without any explicit action on my part. Frequently interfering with my browsing the page, sometimes hanging around until I wiggle the touchpad, sometimes on it's own and sometimes because I used my touch-screen to close a tab -- now my screen is covered up.
This is not great.