' Folgender Code in ein Modul:
 
Option Explicit
 
Public Const MF_STRING = &H0&
Public Const GWL_WNDPROC = (-4&)
Public Const WM_SYSCOMMAND = &H112
 
Public Declare Function GetSystemMenu Lib "user32" (ByVal hwnd As Long, ByVal bRevert As Long) As Long

Public Declare Function AppendMenu Lib "user32" Alias "AppendMenuA" (ByVal hMenu As Long, _
ByVal wFlags As Long, ByVal wIDNewItem As Long, ByVal lpNewItem As String) As Long

Public Declare Function CallWindowProc Lib "user32" Alias "CallWindowProcA" _
(ByVal lpPrevWndFunc As Long, _
ByVal hwnd As Long, ByVal MSG As Long, ByVal wParam As Long, ByVal lParam As Long) As Long

Public Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" (ByVal hwnd As Long, _
ByVal nIndex As Long) As Long

Public Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" (ByVal hwnd As Long, _
ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
 
Public PrevWndProc As Long
 
Public Function SubWndProc(ByVal hwnd As Long, ByVal MSG As Long, _
ByVal wParam As Long, ByVal lParam As Long) As Long
 
Select Case MSG
    Case WM_SYSCOMMAND
        If wParam = &H200 Then
        ' der eigene Eintrag wurde angeklickt!
        MsgBox "Hat geklappt"
        End If
 
    End Select
        'ursprüngliche WinProc aufrufen
        SubWndProc = CallWindowProc(PrevWndProc, hwnd, MSG, wParam, lParam)
End Function