Option Explicit 
 
' benötigte API-Deklarationen
Private Declare Function GetForegroundWindow Lib "user32" () As Long
Private Declare Function GetWindowText Lib "user32" Alias "GetWindowTextA" ( _
    ByVal hwnd As Long, ByVal lpString As String, ByVal cch As Long) As Long
 
 
'Aufruf:
Private Sub Timer1_Timer()
 
    Dim nHWnd As Long
    Dim sTitle As String
    Dim nResult As Long
 
    ' Handle des aktiven Fenster
    nHWnd = GetForegroundWindow()
 
    ' Titel des aktiven Fensters
    sTitle = Space$(255)
    nResult = GetWindowText(nHWnd, sTitle, Len(sTitle))
 
    Label1.Caption = Left$(sTitle, nResult)
End Sub