//一个拦截系统消息的钩子程序事例
static LRESULT CALLBACK LowLevelKeyboardProc(int nCode, WPARAM wParam, LPARAM lParam);
BOOL C**App::InitInstance()
{
   HHOOK hhkKybd  = SetWindowsHookEx(WH_KEYBOARD_LL, LowLevelKeyboardProc,

                                     AfxGetApp()->m_hInstance, 0);
   ///...///
   InitCommonControls();
   CWinApp::InitInstance();
   ///...///
   return TRUE;
}
LRESULT CALLBACK LowLevelKeyboardProc(int nCode, WPARAM wParam, LPARAM lParam)
{

 PKBDLLHOOKSTRUCT p = (PKBDLLHOOKSTRUCT) lParam;

 if (nCode == HC_ACTION)
 {

 int vKey = LOBYTE(p->vkCode);

 //如果为键盘消息

 if (wParam == WM_KEYDOWN)
 {
  switch(vKey)
  {
  case 'd':
  case 'D':
      {
          //如果用户按下了Win + D键盘消息
          if(::GetKeyState(VK_LWIN) < 0) 
          {
            ///do anything here///
          } 
      }
  }
 }
 return CallNextHookEx(NULL, nCode, wParam, lParam);

}