Get Child Window HWND

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1. EnumWindow(hwnd_parent, Fun, lparam)   

　 EnumChildWindow

    SendMessage   可以做单向, 环路通知(最好不要环路, 只剩单向)

2. FindWindow(class_name, window_name)   只找顶层的?

    FindWindowEx(hwnd_parent, xxx, class_name, window_name)   只找1层子窗口?

    GetDlgItem(ID)  只找子控件?

　 GetWindow(hwnd, NEXT|FIRST|OWERN|CHILD)

    GetNextWindow(hwnd, NEXT|PREV)

　 GetTopWindow

3. 记录hwnd (在多线程UI中不好用. 因为UI线程无法传入参数.   g_hwnd 全局不好)

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1. 子窗口 没title.  FindWindow不好使

2. GetDlgItem只能通过控件ID获取控件, 不能获取 子窗口.

3. m_ie.Create(NULL, L"bb", WS_CHILD | WS_VISIBLE | WS_POPUP,  rect, this, 111);

    Create窗口的ID, GetWindowLong(hwnd, GWL_ID); 获取不到.    但tree可以获取到. 

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