<font color="green">'API Mutext erstellen</font>
Private Declare Function CreateMutex Lib "kernel32" Alias "CreateMutexA" _
  (lpMutexAttributes As SECURITY_ATTRIBUTES, ByVal bInitialOwner As Long, _
  ByVal lpName As String) As Long
 
Private Type SECURITY_ATTRIBUTES
  nLength As Long
  lpSecurityDescriptor As Long
  bInheritHandle As Long
End Type
 
Public lngMutex As Long
 
<font color="green">'API Mutext beenden</font>
Private Declare Function CloseHandle Lib "kernel32" _
  (ByVal hObject As Long) As Long
 
Private Sub Form_Load()
  <font color="green">'Mutext erstellen</font>
  lpMutexAttributes.nLength = Len(lpMutexAttributes)
  lngMutex = CreateMutex(lpMutexAttributes, False, "beliebiger String")
End Sub
 
Private Sub Form_Unload()
  <font color="green">'Mutext beenden</font>
  Call CloseHandle(lngMutex)
End Sub