Avoid main window blinking into view when Cancel is pressed in the session manager. Happens because Application.Run() sets the main form to Visible before the message pump starts and gets to processing WM_QUIT (or whatever).

source/main.pas

@@ -1587,7 +1587,7 @@ begin
     FreeAndNil(ConnForm);
     if dlgResult = mrCancel then begin
       Close;
-      Exit;
+      Halt;
     end;
   end;