The CWPRETSTRUCT structure defines the message parameters passed to a WH_CALLWNDPROCRET hook procedure, CallWndRetProc.
typedef struct tagCWPRETSTRUCT { // cwprs
LRESULT lResult;
LPARAM lParam;
WPARAM wParam;
DWORD message;
HWND hwnd;
} CWPRETSTRUCT;
Windows NT: Requires version 3.1 or later.
Windows: Requires Windows 95 or later.
Windows CE: Unsupported.
Header: Declared in winuser.h.
Hooks Overview, Hook Structures, CallWndRetProc, SetWindowsHookEx