Combox滚动条hook

How do I subclass the listbox portion of a combobox? 

The listbox portion of a combobox is of type COMBOLBOX (notice the "L "). Because the ComboLBox window is not a child of the ComboBox window, it is not obvious how to subclass the COMBOLBOX control. Luckily,under the Win32 API, Windows sends a message to the COMBOBOX (notice no "L ") called WM_CTLCOLORLISTBOX before the listbox is drawn. The lParam passed with this message contains the handle of   the list box. 
明白了,可以用枚举线程窗口的方法得到COMBOLBOX这个类的窗口的指针，然后hook它，就挂上滚动条了，因为它不是ComboBox的子窗口，当然不能枚举子窗口了，还有一种方法就是在ComboBox中处理WM_CTLCOLORLISTBOX消息,lparam就是它了，然后hook它，直接hook ComboBox是无效的。

BOOL GetComboBoxInfo(      
    HWND hwndCombo,
    PCOMBOBOXINFO pcbi
);

typedef struct tagCOMBOBOXINFO {
    DWORD cbSize;
    RECT rcItem;
    RECT rcButton;
    DWORD stateButton;
    HWND hwndCombo;
    HWND hwndItem;
    HWND hwndList;//hwndList就是COMBOLBOX的hwnd
} COMBOBOXINFO, *PCOMBOBOXINFO, *LPCOMBOBOXINFO;