docs: private MultiLineRun getMultiLineRun(int offset) {
          MultiLineRun ml = null;
          if (offset > 0) {
              Integer os = offset;
  
              SortedSet set = mlTextRunSet.headSet(os);
              if (!set.isEmpty()) {
                  ml = (MultiLineRun)set.last();
                  ml = ml.end() >= offset ? ml : null;
              }
          }
  
          return ml;
      }