code: void fillFromRight()
    {
      int gapWid = width() - population();
      int gidx = population();
      GBSNode p = rightChild();
      for (int j = 0; j < gapWid; j++)
        _nodeKey[j+gidx] = p._nodeKey[j];
      int delta = gapWid;
      if (p._population < delta)
        delta = p._population;
      _population   += delta;
      p._population -= delta;
      for (int j = 0; j < gidx; j++)
        p._nodeKey[j] = p._nodeKey[j+gapWid];
    }
docs: Fill a node with new keys from the right side.
  
  <p>A node that is not completely full has acquired a right child.
  Use the left keys of the right child to fill the node as much
  as possible, limited by the free space in the current node and
  the population of the right child.</p>