TapHandler {
    gesturePolicy: TapHandler.ReleaseWithinBounds // exclusive grab on press
    onGrabChanged:
        (transition, eventPoint) => {
            switch (transition) {
                case PointerDevice.GrabExclusive:
                    console.log("took exclusive grab of point", eventPoint.id,
                                "on", eventPoint.device.name)
                    break
                case PointerDevice.UngrabExclusive:
                    console.log("gave up exclusive grab of point", eventPoint.id,
                                "on", eventPoint.device.name)
                    break
                case PointerDevice.CancelGrabExclusive:
                    console.log("exclusive grab of point", eventPoint.id,
                                "on", eventPoint.device.name, "has been cancelled")
                    break
            }

            switch (eventPoint.state) {
                case EventPoint.Pressed:
                    console.log("on press @", eventPoint.position);
                    break
                case EventPoint.Updated:
                    console.log("on update @", eventPoint.position);
                    break
                case EventPoint.Released:
                    console.log("on release @", eventPoint.position);
                    break
                default:
                    console.log(eventPoint.position, "state", eventPoint.state)
                    break
            }
        }
}