Deduplicate maybeQuitOnLastWindowClosed handling

The functionality now lives in QGuiApplication, and is triggered
by QGuiApplication and QApplication after dispatching the close
event to the window.

The slight difference between how a Qt GUI and Qt Widget app
determines if a window should contribute to the close-on-quit
behavior has been abstracted into a QWindowPrivate helper.

The additional checks that were in place for skipping out of
the whole maybeQuitOnLastWindowClosed machinery have been kept.

Task-number: QTBUG-53286
Change-Id: I81bd474755f9adb3a2b082621e5ecaa1c4726808
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

1 files changed, 4 insertions, 0 deletions

diff --git a/src/widgets/kernel/qapplication.cpp b/src/widgets/kernel/qapplication.cpp
index 9069b9005d..74868077b3 100644
--- a/src/widgets/kernel/qapplication.cpp
+++ b/src/widgets/kernel/qapplication.cpp
@@ -3342,6 +3342,10 @@ bool QApplication::notify(QObject *receiver, QEvent *e)
         break;
     }
 
+    // We don't call QGuiApplication::notify here, so we need to duplicate the logic
+    if (e->type() == QEvent::Close && receiver->isWindowType() && res)
+        d->maybeQuitOnLastWindowClosed(static_cast<QWindow *>(receiver));
+
     return res;
 }