Hi Richard,

Here is some sample code that displays a DateTimePicker:

/// <summary>
/// DataGridDateTimePickerColumn - Displays a date picker, optionaly
/// displays date in red if in past, and
/// can display a check box to represent DBNull.
/// </summary>
public class DataGridDateTimePickerColumn : DataGridColumnStyle
{
	private DateTimePicker picker;
	private bool editing = false;
	private string originalText;
	private bool _redIfInPast;

	public DataGridDateTimePickerColumn() :
		this(false, false)
	{
	}

	public DataGridDateTimePickerColumn(bool checkBox) :
		this(checkBox, false)
	{
	}

	public DataGridDateTimePickerColumn(bool checkBox, bool redIfInPast)
	{
		picker = new DateTimePicker();

		picker.Visible = false;
		picker.ShowCheckBox = checkBox;
		picker.Format = DateTimePickerFormat.Short;

		RedIfInPast = redIfInPast;
	}

	public bool RedIfInPast
	{
		get {return _redIfInPast;}
		set {_redIfInPast = value;}
	}

	public bool ShowCheckBox
	{
		get {return picker.ShowCheckBox;}
		set {picker.ShowCheckBox = value;}
	}

	protected override void Abort(int row)
	{
		RollBack();
		HideDatePicker();
		EndEdit();
	}

	protected override bool Commit(CurrencyManager cm, int row)
	{
		HideDatePicker();

		if (!editing)
		{
			return true;
		}

		try
		{
			if (picker.Checked)
			{
				SetColumnValueAtRow(cm, row, picker.Value);     
			}
			else
			{
				SetColumnValueAtRow(cm, row, System.DBNull.Value);
			}
		}
		catch
		{
			return false;
		}

		EndEdit();

		return true;
	}

	protected override void ConcedeFocus()
	{
		editing = false;

		HideDatePicker();
	}

	protected override void Edit(CurrencyManager cm, int row, Rectangle
		rect, bool readOnly, string text, bool visible)
	{
		originalText = GetText(GetColumnValueAtRow(cm, row));
		Rectangle originalRect = rect;

		picker.Bounds = rect;
		picker.Visible = visible ? true : false;

		string temp = GetText(GetColumnValueAtRow(cm, row));
		if (temp.Length != 0)
		{
			if (temp == "(None)")
			{
				picker.Checked = false;
			}
			else
			{
				picker.Checked = true;
				picker.Value = DateTime.Parse(temp);
			}
		}

		if (picker.Visible)
		{
			DataGridTableStyle.DataGrid.Invalidate(originalRect);
		}

		if (ReadOnly)
		{
			picker.Enabled = false;
		}

		editing = true;
	}

	protected override int GetMinimumHeight()
	{
		return 0;
	}

	protected override int GetPreferredHeight(Graphics g, object o)
	{
		return 0;
	}

	protected override Size GetPreferredSize(Graphics g, object o)
	{
		return new Size(0, 0);
	}

	protected override void Paint(Graphics g, Rectangle rect,
		CurrencyManager cm, int row)
	{
		Paint(g, rect, cm, row, false);
	}

	protected override void Paint(Graphics g, Rectangle rect,
		CurrencyManager cm, int row, bool alignToRight)
	{
		string text = GetText(GetColumnValueAtRow(cm, row));
		PaintText(g, rect, text, alignToRight);
	}

	protected override void Paint(Graphics g, Rectangle rect,
		CurrencyManager cm, int row, Brush backBrush, Brush foreBrush, bool
		alignToRight)
	{
		string text = GetText(GetColumnValueAtRow(cm, row));
		PaintText(g, rect, text, backBrush, foreBrush, alignToRight);
	}

	protected override void SetDataGridInColumn(DataGrid dg)
	{
		base.SetDataGridInColumn(dg);

		if (picker.Parent != dg)
		{
			if (picker.Parent != null)
			{
				picker.Parent.Controls.Remove(picker);
			}
		}

		if (dg != null)
		{
			dg.Controls.Add(picker);
		}
	}

	protected override void UpdateUI(CurrencyManager cm, int row, string
		text)
	{
		string temp = GetText(GetColumnValueAtRow(cm, row)); 

		if (text != null)
		{
			DateTime dateTime = DateTime.Parse(temp);
			picker.Value = dateTime;
		}
	}

	private void HideDatePicker()
	{
		if (picker.Focused)
		{
			DataGridTableStyle.DataGrid.Focus();
		}

		picker.Visible = false;
	}

	public void EndEdit()
	{
		editing = false;

		Invalidate();
	}

	private int DataGridTableGridLineWidth
	{
		get
		{
			return (DataGridTableStyle.GridLineStyle == DataGridLineStyle.Solid)
				? 1 : 0;
		}
	}

	private string GetText(object o)
	{
		if (o == System.DBNull.Value)
		{
			return NullText;
		}

		if (o != null)
		{
			return o.ToString();
		}
		else
		{
			return string.Empty;
		}
	}

	protected virtual void PaintText(Graphics g, Rectangle rect, string
		text, bool alignToRight)
	{
		Brush backBrush = new SolidBrush(DataGridTableStyle.BackColor);
		Brush foreBrush = new SolidBrush(DataGridTableStyle.ForeColor);

		PaintText(g, rect, text, backBrush, foreBrush, alignToRight);
	}

	protected virtual void PaintText(Graphics g, Rectangle rect, string
		text, Brush backBrush, Brush foreBrush, bool alignToRight)
	{ 
		StringFormat format = new StringFormat();
		if (alignToRight)
		{
			format.FormatFlags = StringFormatFlags.DirectionRightToLeft;
		}

		switch (Alignment)
		{
			case HorizontalAlignment.Left:
				format.Alignment = StringAlignment.Near;
				break;
			case HorizontalAlignment.Right:
				format.Alignment = StringAlignment.Far;
				break;
			case HorizontalAlignment.Center:
				format.Alignment = StringAlignment.Center;
				break;
		}

		format.FormatFlags = StringFormatFlags.NoWrap;

		if (RedIfInPast && text != NullText)
		{
			if (DateTime.Parse(text) < DateTime.Now)
			{
				foreBrush = new SolidBrush(Color.Red);
			}
		}

		g.FillRectangle(backBrush, rect);
		g.DrawString(text, DataGridTableStyle.DataGrid.Font, foreBrush, rect,
			format);

		format.Dispose();
	}

	private void RollBack()
	{
		if (originalText == "(None)")
		{
			picker.Value = DateTime.Parse("1/1/0001");
		}
		else
		{
			picker.Value = DateTime.Parse(originalText);
		}
	}
}

>I recently posted a message asking how to add a ComboBox to a DataGrid. Terry Carroll was gracious enough to walk me thru that, using the approach discussed in the Syncfusion FAQ (http://www.syncfusion.com/FAQ/WinForms/FAQ+c44c.asp)
>
>I tried modifying the DataGridComboBoxColumn class used in the Syncfusion example, but I must be doing something wrong.
>
>Am I even taking the right approach in trying to modify the DataGridComboBoxColumn class, or is there a better/simpler way?
>
>Can someone help me add a DateTimePicker to a DataGrid?
>
>Thank you,
>Rick
>--------------------------------------