窗口过程

• A window class defines the attributes of a window , such as its style , its icon , its cursor , the name of the menu , and the name of the window procedure
  这个窗口类定义了一个窗口的属性，例如它的风格、图标、光标指针、菜单名与窗口过程的名称。
• If the handle to the control has already been created , it hooks the window by creating a pointer to the window s original window procedure for later restoration
  如果已创建了控件的句柄，则该句柄创建一个指针指向窗口的原始窗口过程供以后还原，从而与窗口挂钩。