private static boolean isInterestedInLayer(int layer) {
      return layer != HighlighterLayer.CARET_ROW
             && layer != HighlighterLayer.SELECTION
             && layer != HighlighterLayer.ERROR
             && layer != HighlighterLayer.WARNING
             && layer != HighlighterLayer.ELEMENT_UNDER_CARET;
    }
private static boolean isInterestedInLayer(int layer)