Dim sSatz As String
 
  With Me.RichTextBox1
 
    .Text = ""
    Open "C:\test.txt" For Input As #1
      While Not EOF(1)
        Line Input #1, sSatz
        .Text = .Text & sSatz & vbCrLf
      Wend
    Close #1
 
  End With

  Dim lPos As Long
  Dim sText As String
  Dim bEnde As Boolean
  Dim l As Long
 
  With Me.RichTextBox1
 
    sText = .Text
 
      lPos = 1
      bEnde = False
      While bEnde = False
        l = InStr(lPos, sText, vbCrLf)
        If l > 0 Then
          If l - lPos >= 40 Then
            .SelStart = lPos + 39
            .SelLength = l - lPos - 40
            .SelColor = vbBlue
          End If
        Else
          bEnde = True
        End If
        lPos = lPos + (l - lPos) + 2
      Wend
 
  End With