session - What's the proper response to WM_ENDSESSION with ENDSESSION_CLOSEAPP and wParam == FALSE?

Question

According to the WM_ENDESSION docs, when lParam is ENDSESSION_CLOSEAPP and wParam is FALSE, "the application should not shut down".

• So, should I just ignore that and use the default response?
• What is it's purpose?

(I'm listening to Windows events/messages in Qt (C++) to shutdown some launched processes, but that's just the context and shouldn't have any bearing here...)

Answer 1

Yes, a WM_ENDSESSION with wParam==false is simply for information. Prior to receiving this, your application will have received a WM_QUERYENDSESSION. If you did something to get ready to shut down in response to the WM_QUERYENDSESSION, you can un-do it when/if you received a WM_ENDSESSION with wParam=false. If you haven't taken any steps to start shutting down, you can just return 0.