Option Explicit

Private Sub Form_Load()
  Dim x As Integer

  For x = 0 To 1
    List1(x).AddItem "Porsche"
    List1(x).AddItem "Ferrari"
    List1(x).AddItem "Ford"
    List1(x).AddItem "Renault"
    List1(x).AddItem "Jaguar"
    List1(x).AddItem "Citroen"
    List1(x).AddItem "Mercedes"
    List1(x).AddItem "VW"
    List1(x).AddItem "Opel"
    List1(x).AddItem "Toyota"
    List1(x).AddItem "Honda"
    List1(x).AddItem "BMW"
    List1(x).AddItem "Audi"
  Next
End Sub

Private Sub List1_Click(Index As Integer)
  If Check1.Value = 0 Then Exit Sub

  Select Case Index
    Case 0
      List1(1).ListIndex = List1(Index).ListIndex
      Label1(0).Caption = _
           "Listbox 2 wird mit Listbox 1 synchronisiert."
    Case 1
      List1(0).ListIndex = List1(Index).ListIndex
      Label1(0).Caption = _
           "Listbox 1 wird mit Listbox 2 synchronisiert."
  End Select

  Label1(1).Alignment = Index
  Label1(1).Caption = "Listbox " & Index + 1 & " hat den Fokus."
End Sub

Private Sub List1_Scroll(Index As Integer)
  If Check1.Value = 0 Then Exit Sub

  Select Case Index
    Case 0
      List1(1).TopIndex = List1(Index).TopIndex
    Case 1
      List1(0).TopIndex = List1(Index).TopIndex
  End Select
End Sub