I don't think it does work in all other browsers. At least in Firefox on Linux, the mousemoves are only triggered when the mouse is directly over the page itse

I don't think it does work in all other browsers. At least in Firefox on Linux, the mousemoves are only triggered when the mouse is directly over the page itself, not even when over the tab-bar etc, nor when over the Gnome 3 on-screen keyboard (which overlaps the page).