只需要把
For idx As Integer = idx1 To idx2 Dim dr As DataRow = DataTables("国家").DataRows(idx) '根据行位置从数据表中取得对应的DataRow
改成
Dim drs = DataTables("国家").Select("", "面积 desc")
For idx As Integer = idx1 To idx2 Dim dr As DataRow = drs(idx) '根据行位置从数据表中取得对应的DataRow