@ApiStatus.Internal
  public void removeFocusRegion(@NotNull RangeMarker marker) {
    boolean removed = myFocusMarkerTree.removeInterval((RangeMarkerEx)marker);
    if (removed) mySegmentListeners.forEach(l -> l.focusRegionRemoved(marker));
  }
@ApiStatus.Internal
  public void removeFocusRegion(@NotNull RangeMarker marker)