Sent to a WIMMessageCallback function to allow the caller to abort an imaging operation that is currently processing a file resource.
WIM_MSG_SCANNING wParam = (DWORD) 0; lParam = (DWORD) 0;
To cancel an imaging operation that is in progress, return WIM_MSG_ABORT_IMAGE from the callback function. Otherwise, return WIM_MSG_SUCCESS.
This message is provided to allow applications to abort imaging operations that would otherwise not be aborted until the next WIM_MSG_PROCESS message.