This is a good point, and I'll look to address it in the code before this comes in.  It used to be that the official spec for `requestAnimationFrame` had no way to cancel it and Firefox had support but it was  non-standard.  Looking at the spec on MDN, it looks like we can actually cancel the running request. https://developer.mozilla.org/en-US/docs/Web/API/window.requestAnimationFrame