The SetMessageExtraInfo function sets the extra message information for the current thread. Extra message information is an application- or driver-defined 32-bit value associated with the current thread's message queue. An application can use the GetMessageExtraInfo function to retrieve a thread's extra message information.
LPARAM SetMessageExtraInfo(
LPARAM lParam // application-defined 32-bit value
);
The return value is the previous 32-bit value.
Windows NT: Requires version 3.51 or later.
Windows: Requires Windows 95 or later.
Windows CE: Unsupported.
Header: Declared in winuser.h.
Import Library: Use user32.lib.
Messages and Message Queues Overview, Message and Message Queue Functions, GetMessageExtraInfo