Preventing Windows shut down

Question

To detect and prevent shutdown the computer I use very simple program. It has only one form and one private procedure like below:

TForm3 = class(TForm)
priva         


        

Answer 1

This looks like a bug in Delphi. I suggest you to post this on Quality Central.

Answer 2

I usually run "shutdown -a" command. You can do the same from your code to interrupt Windows from shutdown.

Regards

Answer 3

In all versions should you not be using the FormCloseQuery event?

procedure TForm3.FormCloseQuery(Sender: TObject; var CanClose: Boolean);
begin
  Canclose := Not StillDoingImportantStuff;
end;

Oops - just read comments to "this does not work" :( Is win 7 different?

In all my apps this gets called if windows is trying to shut down...

Answer 4

ShutdownGuard is built with Delphi and it's open source, you can download it tweak it for your needs

Answer 5

EDIT: changed to intercept WM_ENDSESSION instead of WM_QUERYENDSESSION.

As you cannot directly change the behaviour of TApplication, you can install a TApplication message hook instead that neutralizes the WM_ENDSESSION message.

Installing such a hook is quite simple, you only have to add a method similar to the following to your mainform and register the hook in FormCreate.

function TForm25.HookEndSession(var Message: TMessage): Boolean;
begin
  result := false;
  if Message.Msg = WM_ENDSESSION then begin
    Message.Result := 0;
    result := true;
  end;
end;

procedure TForm25.FormCreate(Sender: TObject);
begin
  Application.HookMainWindow(HookEndSession);
end;

Answer 6

Are you testing on the same OS? There are some application shutdown changes in Vista. Read this: Application Shutdown Changes in Windows Vista

If you are testing on the same OS, maybe Delphi 2010 handles WM_ENDSESSION messages in a different way. In Delphi 7, WM_ENDSESSION message are handled in Application.WndProc.