SendKeys is very powerful. You can use SendKeys to send a different keycode from the one that was pressed. For example:

private void TextBox1_KeyDown(object sender, KeyEventArgs e)        {            if (e.KeyCode == Keys.Right)            {                SendKeys.Send("{TAB}");            }            if (e.KeyCode == Keys.Left)            {                SendKeys.Send("+{TAB}");            }       }

“Presses” tab when the Left or Right arrow keys are pressed.