message: Translate scroll movement if the deltaX is the same as the threshold
  Because the threshold is zero and the X movement is zero, we were not translating vertical movement to horizontal scrolling.
  Fixes
diff: @@ -129,7 +129,7 @@ export default class IndicatorScrollbar extends React.Component {
  // the harshness of the scroll behaviour. Should be a value between 0 and 1.
  const yRetention = 1.0;
  - if (Math.abs(e.deltaX) < xyThreshold) {
  + if (Math.abs(e.deltaX) <= xyThreshold) {
  // noinspection JSSuspiciousNameCombination
  this._scrollElement.scrollLeft += e.deltaY * yRetention;
  }
  