code: private void addColumns(MpxjTreeNode parentNode, Table table)
     {
        for (Column column : table.getColumns())
        {
           final Column c = column;
           MpxjTreeNode childNode = new MpxjTreeNode(column)
           {
              @Override public String toString()
              {
                 return c.getTitle();
              }
           };
           parentNode.add(childNode);
        }
     }
docs: Add columns to the tree.
  
  @param parentNode parent tree node
  @param table columns container