Private Sub AddLogLine(ByVal new_text As String)
Const MAX_LINES = 10

Dim all_text As String
Dim num_cr As Integer
Dim pos As Integer

    ' Add the new text at the end of the current text.
    all_text = txtLog.Text & vbCrLf & new_text

    ' Count the carriage returns from back to front.
    pos = InStrRev(all_text, vbCrLf)
    Do While pos > 0
        num_cr = num_cr + 1
        If num_cr >= MAX_LINES Then
            ' Stop here.
            all_text = Mid$(all_text, pos + 2)
            Exit Do
        End If
        pos = InStrRev(all_text, vbCrLf, pos - 2)
    Loop

    ' Display the results and scroll to the bottom.
    txtLog.Text = all_text
    txtLog.SelStart = Len(txtLog.Text)
End Sub