Only quit if there are no visible widgets or windows.

We need to let the QGuiApplication determine whether quitting is appropriate
based on whether there are visible top level QWindows after the last top-level
QWidget was closed.

This solves the issue raised here: http://thread.gmane.org/gmane.comp.lib.qt.user/1880

The transientParent is the QWindow equivalent of parentWidget on QWidget, so the test
in QGuiApplication::shouldQuit is similar to the one in QApplication::shouldQuit.

Change-Id: I500eff8d5887f24415180134b3a4be3c630a896f
Reviewed-by: Bradley T. Hughes <bradley.hughes@nokia.com>

src/gui/kernel/qguiapplication.cpp

@@ -2129,7 +2129,7 @@ bool QGuiApplicationPrivate::shouldQuit()
     QWindowList list = QGuiApplication::topLevelWindows();
     for (int i = 0; i < list.size(); ++i) {
         QWindow *w = list.at(i);
-        if (w->isVisible())
+        if (w->isVisible() && !w->transientParent())
             return false;
     }
     return true;

src/gui/kernel/qwindow.cpp

@@ -1708,7 +1708,7 @@ void QWindowPrivate::maybeQuitOnLastWindowClosed()
         bool lastWindowClosed = true;
         for (int i = 0; i < list.size(); ++i) {
             QWindow *w = list.at(i);
-            if (!w->isVisible())
+            if (!w->isVisible() || w->transientParent())
                 continue;
             lastWindowClosed = false;
             break;

src/widgets/kernel/qapplication.cpp

@@ -2950,7 +2950,7 @@ bool QApplicationPrivate::shouldQuit()
         if (w->isVisible() && !w->parentWidget() && w->testAttribute(Qt::WA_QuitOnClose))
             return false;
     }
-    return true;
+    return QGuiApplicationPrivate::shouldQuit();
 }
 
 /*! \reimp

tests/auto/gui/kernel/qguiapplication/tst_qguiapplication.cpp

@@ -57,6 +57,7 @@ private slots:
     void changeFocusWindow();
     void keyboardModifiers();
     void modalWindow();
+    void quitOnLastWindowClosed();
 };
 
 class DummyWindow : public QWindow
@@ -491,5 +492,67 @@ void tst_QGuiApplication::modalWindow()
     delete window1;
 }
 
+void tst_QGuiApplication::quitOnLastWindowClosed()
+{
+    {
+        int argc = 0;
+        QGuiApplication app(argc, 0);
+
+        QTimer timer;
+        timer.setInterval(100);
+
+        QSignalSpy spy(&app, SIGNAL(aboutToQuit()));
+        QSignalSpy spy2(&timer, SIGNAL(timeout()));
+
+        QPointer<QWindow> mainWindow = new QWindow;
+        QPointer<QWindow> dialog = new QWindow;
+
+        dialog->setTransientParent(mainWindow);
+
+        QVERIFY(app.quitOnLastWindowClosed());
+
+        mainWindow->show();
+        dialog->show();
+
+        timer.start();
+        QTimer::singleShot(1000, mainWindow, SLOT(close())); // This should quit the application
+        QTimer::singleShot(2000, &app, SLOT(quit()));        // This makes sure we quit even if it didn't
+
+        app.exec();
+
+        QCOMPARE(spy.count(), 1);
+        QVERIFY(spy2.count() < 15);      // Should be around 10 if closing caused the quit
+    }
+    {
+        int argc = 0;
+        QGuiApplication app(argc, 0);
+
+        QTimer timer;
+        timer.setInterval(100);
+
+        QSignalSpy spy(&app, SIGNAL(aboutToQuit()));
+        QSignalSpy spy2(&timer, SIGNAL(timeout()));
+
+        QPointer<QWindow> mainWindow = new QWindow;
+        QPointer<QWindow> dialog = new QWindow;
+
+        QVERIFY(!dialog->transientParent());
+        QVERIFY(app.quitOnLastWindowClosed());
+
+        mainWindow->show();
+        dialog->show();
+
+        timer.start();
+        QTimer::singleShot(1000, mainWindow, SLOT(close())); // This should not quit the application
+        QTimer::singleShot(2000, &app, SLOT(quit()));
+
+        app.exec();
+
+        QCOMPARE(spy.count(), 1);
+        QVERIFY(spy2.count() > 15);      // Should be around 20 if closing did not cause the quit
+    }
+}
+
+
 QTEST_APPLESS_MAIN(tst_QGuiApplication)
 #include "tst_qguiapplication.moc"

tests/auto/widgets/kernel/qapplication/tst_qapplication.cpp

@@ -718,6 +718,30 @@ void tst_QApplication::quitOnLastWindowClosed()
         QCOMPARE(timerSpy.count(), 1);
         QCOMPARE(appSpy.count(), 2);
     }
+    {
+        int argc = 0;
+        QApplication app(argc, 0, QApplication::GuiServer);
+        QVERIFY(app.quitOnLastWindowClosed());
+
+        QTimer timer;
+        timer.setInterval(100);
+        QSignalSpy timerSpy(&timer, SIGNAL(timeout()));
+
+        QWindow w;
+        w.show();
+
+        QWidget wid;
+        wid.show();
+
+        timer.start();
+        QTimer::singleShot(1000, &wid, SLOT(close())); // This should NOT quit the application because the
+                                                       // QWindow is still there.
+        QTimer::singleShot(2000, &app, SLOT(quit()));  // This causes the quit.
+
+        app.exec();
+
+        QVERIFY(timerSpy.count() > 15);      // Should be around 20 if closing did not caused the quit
+    }
 }
 
 class PromptOnCloseWidget : public QWidget