解决下DataGrid的有关问题，怎么显示ComboBox

解决下DataGrid的问题，如何显示ComboBox！

我想给DataGrid中添加ComboBox,但是显示不正确。怎么办？

C# code

  DataTable dt = new DataTable();        DataTable dtab = new DataTable();        private void ChooseBtn_Click(object sender, RoutedEventArgs e)        {            dt = GetImportExcel();            if (dt != null && dt.Columns.Count > 0)            {                dtab.Columns.Add("旧的列名");                dtab.Columns.Add("新的列名");                for (int i = 0; i < dt.Columns.Count; i++)                {                    DataRow dr = dtab.NewRow();                    dr[0] = dt.Columns[i].ColumnName;                    dr[1] = GetCombox();                    dtab.Rows.Add(dr);                }                gridheader.ItemsSource = dtab.DefaultView;            }        }        public ComboBox GetCombox()        {            ComboBox com = new ComboBox();            com.Width = 150;            com.Items.Add("姓名");            com.Items.Add("年龄");            com.Items.Add("性别");            com.Items.Add("身高");            com.SelectedIndex = 0;            return com;        }