Do not close LyX in the commitData process (#9277)

Since the logout process still can be canceled here, we should only
check that all dirty buffers are saved and that the session state is
recorded.

Please test, particularly on Windows and OSX, that logging out with LyX
running (both with and without dirty buffers) proceeds sensibly and that
the LyX session is correctly restored when you re-login.

src/frontends/qt4/GuiApplication.cpp

@@ -2648,13 +2648,18 @@ void GuiApplication::unregisterSocketCallback(int fd)
 
 void GuiApplication::commitData(QSessionManager & sm)
 {
-	/// The implementation is required to avoid an application exit
+	/** The implementation is required to avoid an application exit
-	/// when session state save is triggered by session manager.
+	 ** when session state save is triggered by session manager.
-	/// The default implementation sends a close event to all
+	 ** The default implementation sends a close event to all
-	/// visible top level widgets when session managment allows
+	 ** visible top level widgets when session managment allows
-	/// interaction.
+	 ** interaction.
-	/// We are changing that to close all wiew one by one.
+	 ** We are changing that to check the state of each buffer in all
-	/// FIXME: verify if the default implementation is enough now.
+	 ** views and ask the users what to do if buffers are dirty.
+	 ** Furthermore, we save the session state.
+	 ** We do NOT close the views here since the user still can cancel
+	 ** the logout process (see #9277); also, this would hide LyX from
+	 ** an OSes own session handling (application restoration).
+	 **/
 	#ifdef QT_NO_SESSIONMANAGER
 		#ifndef _MSC_VER
 			#warning Qt is compiled without session manager
@@ -2663,8 +2668,10 @@ void GuiApplication::commitData(QSessionManager & sm)
 		#endif
 		(void) sm;
 	#else
-		if (sm.allowsInteraction() && !closeAllViews())
+		if (sm.allowsInteraction() && !prepareAllViewsForLogout())
 			sm.cancel();
+		else
+			sm.release();
 	#endif
 }
 
@@ -2698,6 +2705,21 @@ bool GuiApplication::closeAllViews()
 }
 
 
+bool GuiApplication::prepareAllViewsForLogout()
+{
+	if (d->views_.empty())
+		return true;
+
+	QList<GuiView *> const views = d->views_.values();
+	foreach (GuiView * view, views) {
+		if (!view->prepareAllBuffersForLogout())
+			return false;
+	}
+
+	return true;
+}
+
+
 GuiView & GuiApplication::view(int id) const
 {
 	LAPPERR(d->views_.contains(id));

src/frontends/qt4/GuiApplication.h

@@ -207,6 +207,9 @@ private:
 	void updateCurrentView(FuncRequest const & cmd, DispatchResult & dr);
 	///
 	bool closeAllViews();
+	/// Things that need to be done when the OSes session manager
+	/// requests a log out.
+	bool prepareAllViewsForLogout();
 	/// read the given ui (menu/toolbar) file
 	bool readUIFile(QString const & name, bool include = false);
 	///

src/frontends/qt4/GuiView.cpp

@@ -884,6 +884,32 @@ bool GuiView::closeScheduled()
 }
 
 
+bool GuiView::prepareAllBuffersForLogout()
+{
+	Buffer * first = theBufferList().first();
+	if (!first)
+		return true;
+
+	// First, iterate over all buffers and ask the users if unsaved
+	// changes should be saved.
+	// We cannot use a for loop as the buffer list cycles.
+	Buffer * b = first;
+	do {
+		if (!saveBufferIfNeeded(const_cast<Buffer &>(*b), false))
+			return false;
+		b = theBufferList().next(b);
+	} while (b != first);
+
+	// Next, save session state
+	// When a view/window was closed before without quitting LyX, there
+	// are already entries in the lastOpened list.
+	theSession().lastOpened().clear();
+	writeSession();
+
+	return true;
+}
+
+
 /** Destroy only all tabbed WorkAreas. Destruction of other WorkAreas
  ** is responsibility of the container (e.g., dialog)
  **/

src/frontends/qt4/GuiView.h

@@ -75,6 +75,10 @@ public:
 	/// programmatically and not by the user clicking the x.
 	bool closeScheduled();
 
+	/// Things that need to be done when the OSes session manager
+	/// requests a log out.
+	bool prepareAllBuffersForLogout();
+
 	int id() const { return id_; }
 
 	/// are we busy ?