Canvas.requestAnimationFrame undocumented

The documentation for Canvas.requestAnimationFrame says, briefly:

This function schedules callback to be invoked before composing the Qt Quick scene.

That's not quite enough to implement anything. It does not say what the callback can do and whether it should call requestAnimationFrame again. If I try to use it in trivial HTML-like way, everything explodes: http://stackoverflow.com/questions/30709220/qml-canvas-requestanimationframe-explodes. There does not appear to be any tests for this function, or examples for this function. It would be great if the documentation provides at least some hints as to proper use of this API.