Close widgets properly from session management.

Introduce new virtual QGuiApplicationPrivate::tryCloseAllWindows()
which allows overriding the behavior in QApplication to properly close
the widgets first.

Without this, QGuiApplication closes the widget windows leaving a stale
window handle behind in the associated QWidget which then causes the
application not to terminate since QApplication::shouldQuit() stills
finds the affected widgets to be visible.

Task-number: QTBUG-35986

Change-Id: I19ac4b5a19250ee68d09e461c03dbace458c98e4
Reviewed-by: David Faure <david.faure@kdab.com>

2 files changed, 25 insertions, 17 deletions

diff --git a/src/gui/kernel/qguiapplication.cpp b/src/gui/kernel/qguiapplication.cpp
index 0f3f8d8ff2..3953437372 100644
--- a/src/gui/kernel/qguiapplication.cpp
+++ b/src/gui/kernel/qguiapplication.cpp
@@ -2696,6 +2696,27 @@ bool QGuiApplicationPrivate::shouldQuitInternal(const QWindowList &processedWind
     return true;
 }
 
+bool QGuiApplicationPrivate::tryCloseAllWindows()
+{
+    return tryCloseRemainingWindows(QWindowList());
+}
+
+bool QGuiApplicationPrivate::tryCloseRemainingWindows(QWindowList processedWindows)
+{
+    QWindowList list = QGuiApplication::topLevelWindows();
+    for (int i = 0; i < list.size(); ++i) {
+        QWindow *w = list.at(i);
+        if (w->isVisible() && !processedWindows.contains(w)) {
+            if (!w->close())
+                return false;
+            processedWindows.append(w);
+            list = QGuiApplication::topLevelWindows();
+            i = -1;
+        }
+    }
+    return true;
+}
+
 /*!
     \since 5.2
     \fn Qt::ApplicationState QGuiApplication::applicationState()
@@ -2902,23 +2923,8 @@ void QGuiApplicationPrivate::commitData()
     Q_Q(QGuiApplication);
     is_saving_session = true;
     emit q->commitDataRequest(*session_manager);
-    if (session_manager->allowsInteraction()) {
-        QWindowList done;
-        QWindowList list = QGuiApplication::topLevelWindows();
-        bool cancelled = false;
-        for (int i = 0; !cancelled && i < list.size(); ++i) {
-            QWindow* w = list.at(i);
-            if (w->isVisible() && !done.contains(w)) {
-                cancelled = !w->close();
-                if (!cancelled)
-                    done.append(w);
-                list = QGuiApplication::topLevelWindows();
-                i = -1;
-            }
-        }
-        if (cancelled)
-            session_manager->cancel();
-    }
+    if (session_manager->allowsInteraction() && !tryCloseAllWindows())
+        session_manager->cancel();
     is_saving_session = false;
 }
 
diff --git a/src/gui/kernel/qguiapplication_p.h b/src/gui/kernel/qguiapplication_p.h
index c23232182c..1ec808ec27 100644
--- a/src/gui/kernel/qguiapplication_p.h
+++ b/src/gui/kernel/qguiapplication_p.h
@@ -92,6 +92,7 @@ public:
     virtual bool shouldQuit();
 
     bool shouldQuitInternal(const QWindowList &processedWindows);
+    virtual bool tryCloseAllWindows();
 
     static Qt::KeyboardModifiers modifier_buttons;
     static Qt::MouseButtons mouse_buttons;
@@ -291,6 +292,7 @@ public:
 
 protected:
     virtual void notifyThemeChanged();
+    bool tryCloseRemainingWindows(QWindowList processedWindows);
 #ifndef QT_NO_DRAGANDDROP
     virtual void notifyDragStarted(const QDrag *);
 #endif // QT_NO_DRAGANDDROP