Comment 7 for bug 1697122

BTW I've since changed my mind on this. Setting the proposed environment variable makes toupad scrolling mysteriously slow down after a notification arrives until you switch focus away from Firefox and back (See https://bugzilla.mozilla.org/show_bug.cgi?id=1182700). This problem is particularly severe for mouse scroll wheel users, where wheel scrolling breaks entirely until you switch away and back again.

I grudgingly live with the issue when I'm using a touchpad, but I unset the envar when I'm using a mouse because of how bad it is.

I think https://bugzilla.mozilla.org/show_bug.cgi?id=1182700 needs to be fixed upstream before this can be considered. Unfortunately, it's blocked on a GTK issue (https://gitlab.gnome.org/GNOME/gtk/issues/558) that the GTK developers have declared unfixable on X11.