datagridview control, one text cell with a dynamic button right side, how to do

// This will show a button in the upper right corner
// of a cell in column 0 if a single cell in that
// column is selected or if a single row is selected
//
// button1 is defined elsewhere on the form
// and is initialized with the correct size and is not visible
//
// The click event handler for button1 can display a text box
// at the cell location or take any other appropriate action.

private void dataGridView1_SelectionChanged(object sender, EventArgs e)
{
    const int targetColumn = 0;

    DataGridViewCell cell = null;
    if ((dataGridView1.SelectedCells.Count == 1 &&
        dataGridView1.SelectedCells[0].ColumnIndex == targetColumn) ||
        dataGridView1.SelectedRows.Count == 1)
    {
        cell = dataGridView1.CurrentRow.Cells[targetColumn];
        Rectangle rect = dataGridView1.GetCellDisplayRectangle(cell.ColumnIndex,
            cell.RowIndex, true);
        button1.Parent = dataGridView1;
        button1.Location = new Point(rect.Right - button1.Width, rect.Top);
        button1.Visible = true;
    }
    else
        button1.Visible = false;
}