private void log_notes_sorted_idx(int idx, note_item n) {
if (idx >= 0 && idx < notes_sorted_by_line_index_.Count)
logger.Info("[notes] insert " + n.friendly_note + " before " + notes_sorted_by_line_index_[idx].friendly_note);
else
logger.Info("[notes] adding " + n.friendly_note + " at the end");
}