message: Carried scroller interval tp didMount in react version of progress buttons
diff: @@ -7,17 +7,10 @@ import { SurveyProgressButtonsModel } from '../surveyProgressButtons';
  export class SurveyProgressButtons extends SurveyNavigationBase {
  private progressButtonsModel: SurveyProgressButtonsModel;
  private updateScroller: any = undefined;
  - private isNavigationMounted: boolean = false;
  private listContainerRef: React.RefObject<HTMLDivElement>;
  constructor(props: any) {
  super(props);
  this.progressButtonsModel = new SurveyProgressButtonsModel(this.survey);
  - this.updateScroller = setInterval(() => {
  - if (this.isNavigationMounted) {
  - this.setState({ hasScroller: this.listContainerRef.current.scrollWidth >
  - this.listContainerRef.current.offsetWidth});
  - }
  - }, 100);
  this.listContainerRef = React.createRef();
  }
  render(): JSX.Element {
  @@ -74,10 +67,12 @@ export class SurveyProgressButtons extends SurveyNavigationBase {
  listContainerElement.scrollLeft += (isLeftScroll ? -1 : 1) * 70;
  }
  componentDidMount() {
  - this.isNavigationMounted = true;
  + this.updateScroller = setInterval(() => {
  + this.setState({ hasScroller: this.listContainerRef.current.scrollWidth >
  + this.listContainerRef.current.offsetWidth});
  + }, 100);
  }
  componentWillUnmount() {
  - this.isNavigationMounted = false;
  if (typeof this.updateScroller !== "undefined") {
  clearInterval(this.updateScroller);
  this.updateScroller = undefined;
  