C# Datagridview to textbox

// The following code works perfect for me:

private void dgvCustomers_SelectionChanged(Object sender, EventArgs e)
       {
           MessageBox.Show("SelectionChanged event happened!");

           DataGridViewRow row = this.dgvCustomers.SelectedRows[0];

           txtID.Text = row.Cells[0].Value.ToString();
           txtFirst.Text = row.Cells[1].Value.ToString();
           txtLast.Text = row.Cells[2].Value.ToString();
       }

//BUT, you must enter the following line in the load event
// to 'wire up' the event as there is nothing on the form
// in design view to double-click on to do this!

dgvCustomers.SelectionChanged += dgvCustomers_SelectionChanged;