need a combobox in DataGrid ?

I having been tring to add a combobox to the datagrid. here is da code


using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.Diagnostics;



// Derive class from DataGridTextBoxColumn
public class DataGridComboBoxColumn : DataGridTextBoxColumn
{
// Hosted ComboBox control
private ComboBox comboBox;
private CurrencyManager cm;
private int iCurrentRow;

// Constructor - create combobox, register selection change event handler,
// register lose focus event handler
public DataGridComboBoxColumn()
{
this.cm = null;

// Create ComboBox and force DropDownList style
this.comboBox = new ComboBox();
this.comboBox.DropDownStyle = ComboBoxStyle.DropDownList;

// Add event handler for notification of when ComboBox loses focus
this.comboBox.Leave += new EventHandler(comboBox_Leave);
}

// Property to provide access to ComboBox
public ComboBox ComboBox
{
get { return comboBox; }
}

// On edit, add scroll event handler, and display combo box
protected override void Edit(System.Windows.Forms.CurrencyManager source, int rowNum, System.Drawing.Rectangle bounds, bool readOnly, string instantText, bool cellIsVisible)
{
Debug.WriteLine(String.Format("Edit {0}", rowNum));
base.Edit(source, rowNum, bounds, readOnly, instantText, cellIsVisible);

if (!readOnly && cellIsVisible)
{
// Save current row in the datagrid and currency manager associated with
// the data source for the datagrid
this.iCurrentRow = rowNum;
this.cm = source;

// Add event handler for datagrid scroll notification
this.DataGridTableStyle.DataGrid.Scroll += new EventHandler(DataGrid_Scroll);

// Site the combo box control within the bounds of the current cell
this.comboBox.Parent = this.TextBox.Parent;
Rectangle rect = this.DataGridTableStyle.DataGrid.GetCurrentCellBounds();
this.comboBox.Location = rect.Location;
this.comboBox.Size = new Size(this.TextBox.Size.Width, this.comboBox.Size.Height);

// Set combo box selection to given text
this.comboBox.SelectedIndex = this.comboBox.FindStringExact(this.TextBox.Text);

// Make the ComboBox visible and place on top text box control
this.comboBox.Show();
this.comboBox.BringToFront();
this.comboBox.Focus();
}
}

// Given a row, get the value member associated with a row. Use the value
// member to find the associated display member by iterating over bound datasource
protected override object GetColumnValueAtRow(System.Windows.Forms.CurrencyManager source, int rowNum)
{

if(this.comboBox.DataSource == null) return null;

Debug.WriteLine(String.Format("GetColumnValueAtRow {0}", rowNum));
// Given a row number in the datagrid, get the display member
object obj = base.GetColumnValueAtRow(source, rowNum);

// Iterate through the datasource bound to the ColumnComboBox
// Don't confuse this datasource with the datasource of the associated datagrid
CurrencyManager cm = (CurrencyManager) (this.DataGridTableStyle.DataGrid.BindingContext[this.comboBox.DataSource]);
// Assumes the associated DataGrid is bound to a DataView, or DataTable that
// implements a default DataView
DataView dataview = ((DataView)cm.List);

int i;

for (i = 0; i < dataview.Count; i++)
{
if (obj.Equals(dataview[i][this.comboBox.ValueMember]))
break;
}

if (i < dataview.Count)
return dataview[i][this.comboBox.DisplayMember];

return DBNull.Value;
}

// Given a row and a display member, iterating over bound datasource to find
// the associated value member. Set this value member.
protected override void SetColumnValueAtRow(System.Windows.Forms.CurrencyManager source, int rowNum, object value)
{
Debug.WriteLine(String.Format("SetColumnValueAtRow {0} {1}", rowNum, value));
object s = value;

// Iterate through the datasource bound to the ColumnComboBox
// Don't confuse this datasource with the datasource of the associated datagrid
CurrencyManager cm = (CurrencyManager)
(this.DataGridTableStyle.DataGrid.BindingContext[this.comboBox.DataSource]);
// Assumes the associated DataGrid is bound to a DataView, or DataTable that
// implements a default DataView
DataView dataview = ((DataView)cm.List);
int i;

for (i = 0; i < dataview.Count; i++)
{
if (s.Equals(dataview[i][this.comboBox.DisplayMember]))
break;
}

// If set item was found return corresponding value, otherwise return DbNull.Value
if(i < dataview.Count)
s = dataview[i][this.comboBox.ValueMember];
else
s = DBNull.Value;

base.SetColumnValueAtRow(source, rowNum, s);
}

// On datagrid scroll, hide the combobox
private void DataGrid_Scroll(object sender, EventArgs e)
{
Debug.WriteLine("Scroll");
this.comboBox.Hide();
}

// On combo box losing focus, set the column value, hide the combo box,
// and unregister scroll event handler
private void comboBox_Leave(object sender, EventArgs e)
{


try
{

if(this.comboBox.DisplayMember == "")
{
this.comboBox.Hide();
return;
}

if(this.comboBox.SelectedItem == null)
{
this.comboBox.Hide();
return;
}

DataRowView rowView = (DataRowView) this.comboBox.SelectedItem;
string s = (string) rowView.Row[this.comboBox.DisplayMember];
Debug.WriteLine(String.Format("Leave: {0} {1}", this.comboBox.Text, s));

SetColumnValueAtRow(this.cm, this.iCurrentRow, s);
Invalidate();

this.comboBox.Hide();
this.DataGridTableStyle.DataGrid.Scroll -= new EventHandler(DataGrid_Scroll);

}
finally
{
this.comboBox.Hide();
}

}
}