Private Sub txt1_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles txt1.KeyDown
        If txt1.SelectionStart = txt1.MaxLength And e.KeyCode = Keys.Right Then
            txt2.SelectionStart =  0 
            txt2.Focus()
        End If
    End Sub

    Private Sub txt2_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles txt2.KeyDown
        If txt2.SelectionStart =  0  And e.KeyCode = Keys.Left Then
            txt1.SelectionStart = txt1.MaxLength
            txt1.Focus()
        End If
    End Sub