public void installHighlighter(@NotNull FoldedGroup group) {
      assert myHighlighters.isEmpty();

      for (int i = 0; i < myCount; i++) {
        FoldRegion region = myRegions[i];
        if (region == null || !region.isValid()) continue;
        myHighlighters.addAll(DiffDrawUtil.createLineSeparatorHighlighter(myEditors[i],
                                                                          region.getStartOffset(), region.getEndOffset(),
                                                                          new MySeparatorPresentation(group, i)));
      }
    }
public void installHighlighter(@NotNull FoldedGroup group)