dwThreadId [in] Specifies the identifier of the thread with which the hook procedure is to be associated. If this parameter is zero, the hook procedure is associated with all existing threads running in the same desktop as the calling thread. 如果你想hook某个特殊线程，则设置那个线程序ID,如果你想hook所有的进程，则设置为NULL.
[in] Specifies the identifier of the thread with which the hook procedure is to be associated. If this parameter is zero, the hook procedure is associated with all existing threads running in the same desktop as the calling thread. 如果你想hook某个特殊线程，则设置那个线程序ID,如果你想hook所有的进程，则设置为NULL.