oldText = aktText
 
        Dim sr As New System.IO.StreamReader("all.txt", _
          System.Text.Encoding.Default)
        aktText = (sr.ReadToEnd)
        sr.Close()
 
        Dim LenOld As Integer
        LenOld = Len(oldText)
        TextBox1.Text = Mid$(aktText, LenOld + 1, Len(aktText))

 
Public Function GetEndOfTextFile(ByVal File As String, _
        LengthOfText As Integer) As String
 
        If Not IO.File.Exists(File) Then Return Nothing
        If LengthOfText < 1 Then Return Nothing
 
        Dim fi As New IO.FileInfo(File)
        If fi.Length < 1 Then Return Nothing
        If fi.Length < LengthOfText Then LengthOfText = fi.Length
 
        'Encoding ggf. anpassen  
        Dim enc As System.Text.Encoding = System.Text.Encoding.UTF8
 
        Dim pos As Integer = fi.Length - LengthOfText
        Dim EndOfText(LengthOfText - 1) As Byte
 
        Try
            Using fs As New IO.FileStream(File, _
                IO.FileMode.Open, IO.FileAccess.Read, IO.FileShare.ReadWrite)
 
                fs.Position = pos
                fs.Read(EndOfText, 0, LengthOfText)
            End Using
 
            Return enc.GetString(EndOfText)
        Catch
            Return Nothing
        End Try
    End Function