Public Sub do_subclass()
  lpPrevWndProc = SetWindowLong(Application.hWnd, GWL_WNDPROC, AddressOf _
    fWindowProc)
End Sub
 
Function fWindowProc(ByVal hw As Long, ByVal uMsg As Long, ByVal wParam As _
  Long, ByVal lParam As Long) As Long
    fWindowProc = CallWindowProc(lpPrevWndProc, hw, uMsg, wParam, lParam)
End Function

Public Sub undo_subclass()
  Call SetWindowLong(Application.hWnd, GWL_WNDPROC, lpPrevWndProc)
End Sub

Public Const GWL_WNDPROC = (-4)
Public lpPrevWndProc As Long

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
 
Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" _
   (ByVal hWnd As Long, ByVal nIndex As Long, ByVal dwNewLong As _
   Long) As Long