message: change wording of comment as per Luke's review
diff: @@ -1021,7 +1021,7 @@ var TimelinePanel = React.createClass({
  if ((allowPartial && boundingRect.top < wrapperRect.bottom) ||
  (!allowPartial && boundingRect.bottom < wrapperRect.bottom)) {
  let latestReadEventIndex = i;
  - // Place the RM at a hidden event below the latest seen event (if exists)
  + // Place the RM at a hidden event below the latest visible event.
  // to prevent RM going up the timeline between clients which do not hide the same events.
  for (let j = i + 1; j < this.state.events.length; j++) {
  if (messagePanel._shouldShowEvent(this.state.events[j])) break;
  