' zunächst die benötigten API-Deklarationen
Private Declare Function FindWindow Lib "user32" _
  Alias "FindWindowA" (ByVal sClassName As String, _
  ByVal lpWindowName As String) As Long
 
Private Declare Function SendMessage Lib "user32" Alias _
  "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, _
  ByVal wParam As Long, lParam As Any) As Long
 
Const WM_SYSCOMMAND = &H112
Const SC_CLOSE = &HF060
Const LNULL = 0&
 
 
Public Function CloseWindow(sTitle As String) As Boolean
  Dim lRet As Long
 
  lHandle = FindWindow(vbNullString, sTitle)
  If lHandle <> 0 Then
    lRet = SendMessage(lHandle, WM_SYSCOMMAND, _
      SC_CLOSE, LNULL)
  End If
 
  CloseWindow = (lHandle <> 0)
End Function

CloseWindow "MyApp" 'Irgendeine Anwendung

CloseWindows "Azureus"