Option Compare Database
Option Explicit

Private Const WM_ACTIVATEAPP = &H1C
    
Private 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
    
Private Declare Function SetWindowLong Lib  "User32"  Alias  "SetWindowLongA"  _
 (ByVal hWnd As Long, ByVal nIndex As Long, ByVal wNewWord As Long) As Long
 
Private lpPrevWndProc  As Long
Private Const GWL_WNDPROC  As Long = (- 4 )

Private Function WndProc(ByVal hWnd As Long, ByVal Msg As Long, _
                         ByVal wParam As Long, ByVal lParam As Long) As Long
 Select Case Msg
  Case WM_ACTIVATEAPP:
   Debug.Print  "Activate - "  & wParam &  " - "  & lParam
 End Select
 WndProc = CallWindowProc(lpPrevWndProc, hWnd, Msg, wParam, lParam)
End Function

Public Sub Hook()
 lpPrevWndProc = SetWindowLong(Application.hWndAccessApp, GWL_WNDPROC, AddressOf WndProc)
End Sub

Public Sub Unhook()
 SetWindowLong Application.hWndAccessApp, GWL_WNDPROC, lpPrevWndProc
End Sub