Private Sub UnZip(ByVal ZipFileName As String, _
                  ByVal Targetdirectory As String, _
                  Optional prb As ProgressBar = Nothing)
 
        Dim IzipDatei As ZipFile = New ZipFile(ZipFileName)
 
        Dim files As New List(Of String)
        For i As Long = 0 To IzipDatei.Count - 1
            Dim ze As ZipEntry = IzipDatei.EntryByIndex(CInt(i))
            files.Add(ze.Name)
        Next i
        If files.Count = 0 Then Exit Sub
 
        If prb IsNot Nothing Then
            prb.Minimum = 0 : prb.Maximum = files.Count
        End If
 
        Dim Entpacker As New ICSharpCode.SharpZipLib.Zip.FastZip
 
        For i As Integer = 0 To files.Count - 1
            Entpacker.ExtractZip(ZipFileName, Targetdirectory, files(i))
            If prb IsNot Nothing Then
                prb.Value = i + 1
                prb.Refresh()
            End If
        Next i
    End Sub