Private onMouseMove
onMouseMove: function = throttle((event) => {const normalized = normalizeEvent(event, this.state.chartRect);// movenmentX/movenmentY aren't supported by safari/ie https://developer.mozilla.org/en-US/docs/Web/API/MouseEvent/movementX#Browser_compatibilityif (this.moveState) {this.curtain.move(this.moveState.target, normalized.clientX - this.moveState.previousMouseMoveEvent.clientX);this.moveState.previousMouseMoveEvent = normalized;}}, MOUSE_MOVE_THROTTLE)