说明：  控件通过向父窗口发送控件通知消息来表明发生了某种事件．例如，当用户在按钮上单击鼠标时，按钮控件会向父窗口发送BN_CLICKED消息．传统控件的通知消息实际上是通过WM_COMMAND消息发给父窗口的（滚动条除外），在该消息的wParam中含有通知消息码（如BN_CLICKED）和控件的ID，在lParam中则包含了控件的句
(Controls window by the father to send information to notify the Control show the occurrence of certain events. For example, when users click of the mouse button, the button control to the parent window will be sent BN_CLICKED news. Traditional Control informed the news is actually WM_COMMAND news circulated through the window of the father (except rolling), in the news wParam contains alerts code (such as BN_CLICKED) and the control ID, lParam which contains the control of the sentence)