private static void clearMarkers(Caret caret) {
      Couple<RangeMarker> markers = caret.getUserData(MARKERS_KEY);
      if (markers != null) {
        allMarkers.remove(markers.first);
        allMarkers.remove(markers.second);
        markers.first.dispose();
        markers.second.dispose();
        caret.putUserData(MARKERS_KEY, null);
      }
    }
private static void clearMarkers(Caret caret)