MSDN自带的多线程例子mtgdi中的疑问？？？？？？？

代码如下：
void CThreadView::OnKillThreads()
{
  // tell all threads to shutdown
  for (POSITION pos = m_threadList.GetHeadPosition(); pos != NULL; )
 {
CGDIThread* pThread = m_threadList.GetNext(pos);
VERIFY(SetEvent(pThread->m_hEventKill));
 }
 
 // wait for all threads to finish shutdown
 for (int nThreadsLeft = m_threadList.GetCount(); nThreadsLeft != 0; )
 {
   //×××××××××××××××××××《1》
    WaitForSingleObject(CGDIThread::m_hAnotherDead, INFINITE);
    Sleep(nThreadsLeft*2);// 200ms for every 100 threads
    nThreadsLeft = 0;
   for (pos = m_threadList.GetHeadPosition(); pos != NULL; )
{
CGDIThread* pThread = m_threadList.GetNext(pos);
if (WaitForSingleObject(pThread->m_hEventDead, 0) ==  WAIT_TIMEOUT)
++nThreadsLeft;
}
UpdateTitle(nThreadsLeft);
 }  // delete all thread objects
  while (!m_threadList.IsEmpty())
 {
CGDIThread* pThread = m_threadList.RemoveHead();
VERIFY(WaitForSingleObject(pThread->m_hThread, INFINITE) == WAIT_OBJECT_0);
delete pThread;
 }
 UpdateTitle(); // invalidate the window since all threads are now gone
 Invalidate();
}单步跟踪时，为什么会从《1》跳到《2》中，此前，CGDIThread::m_hAnotherDead并没有被操作过的。void CGDIThread::Delete()
{
       //×××××××××××××××××××《2》
CWinThread::Delete(); // acknowledge receipt of kill notification
VERIFY(SetEvent(m_hEventDead));
VERIFY(SetEvent(m_hAnotherDead));
}这个例子位于..\samples\VC98\mfc\advanced 目录下的。谢谢解答。