Private Sub Form_Load()
  Call SetCBTHook
End Sub

Private Sub Form_QueryUnload(Cancel As Integer, UnloadMode As Integer)
  If IsHooked Then
    Call RemoveCBTHook
  End If
End Sub

Option Explicit

Private Declare Function SetWindowsHookEx Lib "user32" Alias "SetWindowsHookExA" (ByVal idHook As Long, ByVal lpfn As Long, ByVal hmod As Long, ByVal dwThreadId As Long) As Long
Private Declare Function UnhookWindowsHookEx Lib "user32" (ByVal hHook As Long) As Long
Private Declare Function CallNextHookEx Lib "user32" (ByVal hHook As Long, ByVal ncode As Long, ByVal wParam As Long, lParam As Any) As Long

Public Const WH_CBT = 5
Public Const WH_KEYBOARD = 2

Public Const HCBT_KEYSKIPPED = 7
Public Const HCBT_SYSCOMMAND = 8

Private hHook As Long
Private hKbdHook As Long

Public IsHooked As Boolean

Public Sub SetCBTHook()
  If Not IsHooked Then
    hHook = SetWindowsHookEx(WH_CBT, AddressOf CBTProc, 0, App.ThreadID)
    hKbdHook = SetWindowsHookEx(WH_KEYBOARD, AddressOf KbdProc, 0, App.ThreadID)
    IsHooked = True
  End If
End Sub

Public Sub RemoveCBTHook()
  Dim temp As Long
  temp = UnhookWindowsHookEx(hHook)
  temp = UnhookWindowsHookEx(hKbdHook)
  IsHooked = False
End Sub

Public Function CBTProc(ByVal uCode As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
  If uCode = HCBT_SYSCOMMAND Then
    If wParam = 61824 Then
      CBTProc = -1
      MsgBox "Eigene Hilfe!"
    End If
  ElseIf uCode = HCBT_KEYSKIPPED Then
    Debug.Print wParam
      If wParam = 112 Then
        CBTProc = -1
        MsgBox "Eigene Hilfe!"
      End If
  End If  
  If CBTProc = -1 Then
    CBTProc = 1
  Else
    CBTProc = CallNextHookEx(hHook, uCode, wParam, lParam)
  End If
End Function

Public Function KbdProc(ByVal uCode As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
  KbdProc = CallNextHookEx(hKbdHook, uCode, wParam, lParam)
End Function