This hook is called whenever WinGetMsg, WinWaitMsg, or WinPeekMsg are used to filter message identities.
#define INCL_WINHOOKS /* Or use INCL_WIN, INCL_PM, */
#include <os2.h>
HAB hab; /* Anchor-block handle. */
PQMSG pQmsg; /* Pointer to the QMSG structure of the message currently being reviewed. */
ULONG usFirst; /* First message identity specified on a call to the WinGetMsg, WinPeekMsg or WinWaitMsg function. */
ULONG usLast; /* Last message identity specified on a call to the WinGetMsg, WinPeekMsgor WinWaitMsg function. */
ULONG fOptions; /* Message removal options. */
BOOL rc; /* Processing indicator. */
rc = CheckMsgFilterHook(hab, pQmsg, usFirst,
usLast, fOptions);