顶层窗口 meaning in English

top-level window

When memory pressure from running applications is intensive , windows ce sends the wm hibernate message to top level windows
当正在运行的应用程序导致内存告急时， windows ce会向顶层窗口发送wm _ hibernate消息。
Returns a pointer to the foreground window ( the window with which the user is currently working ) . the foreground window applies only to top - level windows ( frame windows or dialog boxes )
返回指向前台窗口（用户正在其中工作的窗口）的指针。前台窗口仅适用于顶层窗口（框架窗口或对话框）。