message: Adjust IndicatorScrollbar to not rely on AutoHideScrollbar for overflow
diff: @@ -66,6 +66,22 @@ export default class IndicatorScrollbar extends React.Component {
  this._autoHideScrollbar = autoHideScrollbar;
  }
  +
  + componentDidUpdate(prevProps) {
  + const prevLen = prevProps && prevProps.children && prevProps.children.length || 0;
  + const curLen = this.props.children && this.props.children.length || 0;
  + // check overflow only if amount of children changes.
  + // if we don't guard here, we end up with an infinite
  + // render > componentDidUpdate > checkOverflow > setState > render loop
  + if (prevLen !== curLen) {
  + this.checkOverflow();
  + }
  + }
  +
  + componentDidMount() {
  + this.checkOverflow();
  + }
  +
  checkOverflow() {
  const hasTopOverflow = this._scrollElement.scrollTop > 0;
  const hasBottomOverflow = this._scrollElement.scrollHeight >
  @@ -95,10 +111,6 @@ export default class IndicatorScrollbar extends React.Component {
  this._scrollElement.classList.remove("mx_IndicatorScrollbar_rightOverflow");
  }
  - if (this._autoHideScrollbar) {
  - this._autoHideScrollbar.checkOverflow();
  - }
  -
  if (this.props.trackHorizontalOverflow) {
  this.setState({
  // Offset from absolute position of the container
  