Here is code that I have discovered works
let win = window.wrappedJSObject;
exportFunction(onScroll, win, {defineAs: 'onScroll'});
win.eval("addEventListener('scroll', onScroll, true);");
function onScroll(ev)
{
ev.stopPropagation();
}
Anything else results in permission errors.
Is this: the best way to do it; the only way to do it; or about to be prevented by future changes?