richTextBox.SelectionBackColor in a datagridview with AlternatingRowsDefaultCellStyle

Hello

In this code:

dataGridView1.AlternatingRowsDefaultCellStyle.BackColor = Color.Linen;
for (int i = 0; i < dt.Rows.Count; i++)
                    {
                        richTextBox1.SelectAll();
                        richTextBox1.SelectionColor = Color.Black;
                        if (i%2 > 0)
                            richTextBox1.SelectionBackColor = Color.Linen;
                        else
                        richTextBox1.SelectionBackColor = Color.White;
                        richTextBox1.Text = dt.Rows[i][0].ToString();
                        richTextBox2.Text = dt.Rows[i][1].ToString();
                        if (richTextBox1.Text.IndexOf(textBox1.Text) >= 0)
                        {
                            richTextBox1.Select(richTextBox1.Text.IndexOf(textBox1.Text), textBox1.Text.Length);
                            richTextBox1.SelectionBackColor = Color.LightGray;
                        }
                        dataGridView1.Rows[i].Cells[0].Value = richTextBox1.Rtf;
                        dataGridView1.Rows[i].Cells[1].Value = richTextBox2.Rtf;
                    }

output is: