Index: src/kmainwindow.cpp
===================================================================
--- src/kmainwindow.cpp
+++ src/kmainwindow.cpp
@@ -174,10 +174,7 @@
 
     /*
        Purpose of this exercise: invoke queryClose() without actually closing the
-       windows, because
-       - queryClose() may contain session management code, so it must be invoked
-       - actually closing windows may quit the application - cf.
-         QGuiApplication::quitOnLastWindowClosed()
+       application, because
        - quitting the application and thus closing the session manager connection
          violates the X11 XSMP protocol.
          The exact requirement of XSMP that would be broken is,
@@ -189,18 +186,18 @@
          Worst of all, that is a real problem with ksmserver - it will not save
          applications that quit on their own in state save-yourself-done.
      */
+    QGuiApplication::setQuitOnLastWindowClosed(false);
     const auto windows = KMainWindow::memberList();
     for (KMainWindow *window : windows) {
         if (window->testAttribute(Qt::WA_WState_Hidden)) {
             continue;
         }
-        QCloseEvent e;
-        QApplication::sendEvent(window, &e);
-        if (!e.isAccepted()) {
+        if (!window->close()) {
             sm.cancel();
-            return;
+            break;
         }
     }
+    QGuiApplication::setQuitOnLastWindowClosed(true);
 }
 
 Q_GLOBAL_STATIC(KMWSessionManager, ksm)