Private Sub rtf_TextChanged(sender As Object, _
        e As System.EventArgs) Handles rtf.TextChanged
 
        Me.Text = CStr(RTF_TOPLINENUMBER())
    End Sub
 
    Private Sub rtf_VScroll(sender As Object, _
        e As System.EventArgs) Handles rtf.VScroll
 
        Me.Text = CStr(RTF_TOPLINENUMBER())
    End Sub
 
    Private Function RTF_TOPLINENUMBER() As Integer
 
        Dim ci As Integer = _
           rtf.GetCharIndexFromPosition(New Point(rtf.Left, rtf.Top))
 
        Return rtf.GetLineFromCharIndex(ci)
 
    End Function