Merge remote-tracking branch 'origin/5.6.0' into 5.6

Change-Id: Iac8ff05cd76cbacf859138a73e8e2ed0a979c75a

5 files changed, 76 insertions, 12 deletions

diff --git a/src/gui/doc/snippets/code/src_gui_kernel_qguiapplication.cpp b/src/gui/doc/snippets/code/src_gui_kernel_qguiapplication.cpp
index 4ddf8c8acb..63fdb3bdd0 100644
--- a/src/gui/doc/snippets/code/src_gui_kernel_qguiapplication.cpp
+++ b/src/gui/doc/snippets/code/src_gui_kernel_qguiapplication.cpp
@@ -53,6 +53,7 @@ int main(int argc, char *argv[])
 MyMainWidget::MyMainWidget(QWidget *parent)
     :QWidget(parent)
 {
+    QGuiApplication::setFallbackSessionManagementEnabled(false);
     connect(qApp, SIGNAL(commitDataRequest(QSessionManager)), SLOT(commitData(QSessionManager)));
 }
 
diff --git a/src/gui/kernel/qguiapplication.cpp b/src/gui/kernel/qguiapplication.cpp
index 385264d70a..834449fec6 100644
--- a/src/gui/kernel/qguiapplication.cpp
+++ b/src/gui/kernel/qguiapplication.cpp
@@ -138,6 +138,10 @@ QPlatformTheme *QGuiApplicationPrivate::platform_theme = 0;
 
 QList<QObject *> QGuiApplicationPrivate::generic_plugin_list;
 
+#ifndef QT_NO_SESSIONMANAGER
+bool QGuiApplicationPrivate::is_fallback_session_management_enabled = true;
+#endif
+
 enum ApplicationResourceFlags
 {
     ApplicationPaletteExplicitlySet = 0x1,
@@ -3091,6 +3095,57 @@ void QGuiApplicationPrivate::setApplicationState(Qt::ApplicationState state, boo
     emit qApp->applicationStateChanged(applicationState);
 }
 
+#ifndef QT_NO_SESSIONMANAGER
+// ### Qt6: consider removing the feature or making it less intrusive
+/*!
+    \since 5.6
+
+    Returns whether QGuiApplication will use fallback session management.
+
+    The default is \c true.
+
+    If this is \c true and the session manager allows user interaction,
+    QGuiApplication will try to close toplevel windows after
+    commitDataRequest() has been emitted. If a window cannot be closed, session
+    shutdown will be canceled and the application will keep running.
+
+    Fallback session management only benefits applications that have an
+    "are you sure you want to close this window?" feature or other logic that
+    prevents closing a toplevel window depending on certain conditions, and
+    that do nothing to explicitly implement session management. In applications
+    that \e do implement session management using the proper session management
+    API, fallback session management interferes and may break session
+    management logic.
+
+    \warning If all windows \e are closed due to fallback session management
+    and quitOnLastWindowClosed() is \c true, the application will quit before
+    it is explicitly instructed to quit through the platform's session
+    management protocol. That violation of protocol may prevent the platform
+    session manager from saving application state.
+
+    \sa setFallbackSessionManagementEnabled(),
+    QSessionManager::allowsInteraction(), saveStateRequest(),
+    commitDataRequest(), {Session Management}
+*/
+bool QGuiApplication::isFallbackSessionManagementEnabled()
+{
+    return QGuiApplicationPrivate::is_fallback_session_management_enabled;
+}
+
+/*!
+   \since 5.6
+
+    Sets whether QGuiApplication will use fallback session management to
+    \a enabled.
+
+    \sa isFallbackSessionManagementEnabled()
+*/
+void QGuiApplication::setFallbackSessionManagementEnabled(bool enabled)
+{
+    QGuiApplicationPrivate::is_fallback_session_management_enabled = enabled;
+}
+#endif // QT_NO_SESSIONMANAGER
+
 /*!
     \since 4.2
     \fn void QGuiApplication::commitDataRequest(QSessionManager &manager)
@@ -3115,7 +3170,8 @@ void QGuiApplicationPrivate::setApplicationState(Qt::ApplicationState state, boo
 
     \note You should use Qt::DirectConnection when connecting to this signal.
 
-    \sa isSessionRestored(), sessionId(), saveStateRequest(), {Session Management}
+    \sa setFallbackSessionManagementEnabled(), isSessionRestored(),
+    sessionId(), saveStateRequest(), {Session Management}
 */
 
 /*!
@@ -3245,9 +3301,13 @@ void QGuiApplicationPrivate::commitData()
 {
     Q_Q(QGuiApplication);
     is_saving_session = true;
+
     emit q->commitDataRequest(*session_manager);
-    if (session_manager->allowsInteraction() && !tryCloseAllWindows())
+    if (is_fallback_session_management_enabled && session_manager->allowsInteraction()
+        && !tryCloseAllWindows()) {
         session_manager->cancel();
+    }
+
     is_saving_session = false;
 }
 
diff --git a/src/gui/kernel/qguiapplication.h b/src/gui/kernel/qguiapplication.h
index d995387d66..3f233d4eda 100644
--- a/src/gui/kernel/qguiapplication.h
+++ b/src/gui/kernel/qguiapplication.h
@@ -152,6 +152,9 @@ public:
     QString sessionId() const;
     QString sessionKey() const;
     bool isSavingSession() const;
+
+    static bool isFallbackSessionManagementEnabled();
+    static void setFallbackSessionManagementEnabled(bool);
 #endif
 
     static void sync();
diff --git a/src/gui/kernel/qguiapplication_p.h b/src/gui/kernel/qguiapplication_p.h
index 9e157aad51..306d76c5f0 100644
--- a/src/gui/kernel/qguiapplication_p.h
+++ b/src/gui/kernel/qguiapplication_p.h
@@ -236,6 +236,7 @@ public:
 #endif
 
 #ifndef QT_NO_SESSIONMANAGER
+    static bool is_fallback_session_management_enabled;
     QSessionManager *session_manager;
     bool is_session_restored;
     bool is_saving_session;
diff --git a/src/gui/kernel/qsessionmanager.cpp b/src/gui/kernel/qsessionmanager.cpp
index f4b56fd01b..c6d23f163c 100644
--- a/src/gui/kernel/qsessionmanager.cpp
+++ b/src/gui/kernel/qsessionmanager.cpp
@@ -64,22 +64,21 @@ QT_BEGIN_NAMESPACE
     settings.
 
     QSessionManager provides an interface between the application and the
-    session manager so that the program can work well with the session manager.
-    In Qt, session management requests for action are handled by the two
-    signals QGuiApplication::commitDataRequest() and
-    QGuiApplication::saveStateRequest(). Both provide a reference to a session
-    manager object as argument, to allow the application to communicate with
-    the session manager. The session manager can only be accessed through these
-    functions.
+    platform's session manager. In Qt, session management requests for action
+    are handled by the two signals QGuiApplication::commitDataRequest() and
+    QGuiApplication::saveStateRequest(). Both provide a reference to a
+    QSessionManager object as argument. The session manager can only be
+    accessed in slots invoked by these signals.
+
+    \warning If you use QSessionManager, you should disable fallback session
+    management: QGuiApplication::setFallbackSessionManagementEnabled().
 
     No user interaction is possible \e unless the application gets explicit
     permission from the session manager. You ask for permission by calling
     allowsInteraction() or, if it is really urgent, allowsErrorInteraction().
     Qt does not enforce this, but the session manager may.
 
-    You can try to abort the shutdown process by calling cancel(). The default
-    commitData() function does this if some top-level window rejected its
-    closeEvent().
+    You can try to abort the shutdown process by calling cancel().
 
     For sophisticated session managers provided on Unix/X11, QSessionManager
     offers further possibilities to fine-tune an application's session