--- a/libgui/src/dialog.cc	Fri Apr 17 18:16:51 2015 -0700
+++ b/libgui/src/dialog.cc	Fri Apr 17 00:38:40 2015 -0500
@@ -62,6 +62,9 @@
 void
 QUIWidgetCreator::dialog_button_clicked (QAbstractButton *button)
 {
+  // Wait for link thread to go to sleep state.
+  mutex.lock ();
+
   // Store the value so that builtin functions can retrieve.
   if (button)
     dialog_button = button->text ();
@@ -69,6 +72,8 @@
   // The value should always be 1 for the Octave functions.
   dialog_result = 1;
 
+  mutex.unlock ();
+
   // Wake up Octave process so that it continues.
   waitcondition.wakeAll ();
 }
@@ -78,10 +83,15 @@
 QUIWidgetCreator::list_select_finished (const QIntList& selected,
                                         int button_pressed)
 {
+  // Wait for link thread to go to sleep state.
+  mutex.lock ();
+
   // Store the value so that builtin functions can retrieve.
   *list_index = selected;
   dialog_result = button_pressed;
 
+  mutex.unlock ();
+
   // Wake up Octave process so that it continues.
   waitcondition.wakeAll ();
 }
@@ -90,10 +100,15 @@
 void
 QUIWidgetCreator::input_finished (const QStringList& input, int button_pressed)
 {
+  // Wait for link thread to go to sleep state.
+  mutex.lock ();
+
   // Store the value so that builtin functions can retrieve.
   *string_list = input;
   dialog_result = button_pressed;
 
+  mutex.unlock ();
+
   // Wake up Octave process so that it continues.
   waitcondition.wakeAll ();
 }
@@ -102,11 +117,16 @@
 QUIWidgetCreator::filedialog_finished (const QStringList& files,
                                        const QString& path, int filterindex)
 {
+  // Wait for link thread to go to sleep state.
+  mutex.lock ();
+
   // Store the value so that builtin functions can retrieve.
   *string_list = files;
   dialog_result = filterindex;
   *path_name = path;
 
+  mutex.unlock ();
+
   // Wake up Octave process so that it continues.
   waitcondition.wakeAll ();
 }

--- a/libgui/src/dialog.h	Fri Apr 17 18:16:51 2015 -0700
+++ b/libgui/src/dialog.h	Fri Apr 17 00:38:40 2015 -0500
@@ -114,11 +114,11 @@
 
   const QString *get_dialog_path (void) { return path_name; }
 
-  void wait (void)
-  {
-    // Wait while the user is responding to message box.
-    waitcondition.wait (&mutex);
-  }
+  // GUI objects cannot be accessed in the non-GUI thread.  However,
+  // signals can be sent to slots across threads with proper
+  // synchronization.  Hence, the use of QWaitCondition.
+  QMutex mutex;
+  QWaitCondition waitcondition;
 
 signals:
 
@@ -159,13 +159,6 @@
 
   QString *path_name;
 
-  // GUI objects cannot be accessed in the non-GUI thread.  However,
-  // signals can be sent to slots across threads with proper
-  // synchronization.  Hence, the use of QWaitCondition.
-
-  QMutex mutex;
-
-  QWaitCondition waitcondition;
 };
 
 extern QUIWidgetCreator uiwidget_creator;

--- a/libgui/src/main-window.cc	Fri Apr 17 18:16:51 2015 -0700
+++ b/libgui/src/main-window.cc	Fri Apr 17 00:38:40 2015 -0500
@@ -794,10 +794,16 @@
 #endif
     }
 
+  // Wait for link thread to go to sleep state.
+  _octave_qt_link->mutex.lock ();
+
   _octave_qt_link->shutdown_confirmation (closenow);
 
+  _octave_qt_link->mutex.unlock ();
+
   // Awake the worker thread so that it continues shutting down (or not).
   _octave_qt_link->waitcondition.wakeAll ();
+
 }
 
 void

--- a/libgui/src/octave-qt-link.cc	Fri Apr 17 18:16:51 2015 -0700
+++ b/libgui/src/octave-qt-link.cc	Fri Apr 17 00:38:40 2015 -0500
@@ -56,6 +56,10 @@
   command_interpreter->moveToThread (main_thread);
 
   main_thread->start ();
+
+  // Move this link object affinity to the same thread as the
+  // interpreter to ensure signals/slots to the GUI are queued.
+  moveToThread (main_thread);
 }
 
 octave_qt_link::~octave_qt_link (void) { }
@@ -69,12 +73,18 @@
 bool
 octave_qt_link::do_confirm_shutdown (void)
 {
+  // Lock the mutex before emitting signal.
+  mutex.lock ();
+
   emit confirm_shutdown_signal ();
 
   // Wait while the GUI shuts down.
   waitcondition.wait (&mutex);
 
-  // The GUI has sent a signal and the process has been awakened.
+  // The GUI has sent a signal and the thread has been awakened.
+
+  mutex.unlock ();
+
   return _shutdown_confirm_result;
 }
 
@@ -110,6 +120,9 @@
   role << "YesRole" << "RejectRole";
   btn << tr ("Create") << tr ("Cancel");
 
+  // Lock mutex before signaling.
+  uiwidget_creator.mutex.lock ();
+
   uiwidget_creator.signal_dialog (
     tr ("File\n%1\ndoes not exist. Do you want to create it?").
     arg (QDir::currentPath () + QDir::separator ()
@@ -117,10 +130,14 @@
     tr ("Octave Editor"), "quest", btn, tr ("Create"), role );
 
   // Wait while the user is responding to message box.
-  uiwidget_creator.wait ();
-  // The GUI has sent a signal and the process has been awakened.
+  uiwidget_creator.waitcondition.wait (&uiwidget_creator.mutex);
+
+  // The GUI has sent a signal and the thread has been awakened.
+
   QString answer = uiwidget_creator.get_dialog_button ();
 
+  uiwidget_creator.mutex.unlock ();
+
   return (answer == tr ("Create"));
 }
 
@@ -129,6 +146,9 @@
                                    const std::string& msg,
                                    const std::string& title)
 {
+  // Lock mutex before signaling.
+  uiwidget_creator.mutex.lock ();
+
   uiwidget_creator.signal_dialog (QString::fromStdString (msg),
                                   QString::fromStdString (title),
                                   QString::fromStdString (dlg),
@@ -136,10 +156,15 @@
                                   QStringList ());
 
   // Wait while the user is responding to message box.
-  uiwidget_creator.wait ();
+  uiwidget_creator.waitcondition.wait (&uiwidget_creator.mutex);
+
+  // The GUI has sent a signal and the thread has been awakened.
 
-  // The GUI has sent a signal and the process has been awakened.
-  return uiwidget_creator.get_dialog_result ();
+  int answer = uiwidget_creator.get_dialog_result ();
+
+  uiwidget_creator.mutex.unlock ();
+
+  return answer;
 }
 
 std::string
@@ -160,6 +185,9 @@
     btn << QString::fromStdString (btn2);
   btn << QString::fromStdString (btn3);
 
+  // Lock mutex before signaling.
+  uiwidget_creator.mutex.lock ();
+
   uiwidget_creator.signal_dialog (QString::fromStdString (msg),
                                   QString::fromStdString (title),
                                   "quest",
@@ -168,10 +196,15 @@
                                   role);
 
   // Wait while the user is responding to message box.
-  uiwidget_creator.wait ();
+  uiwidget_creator.waitcondition.wait (&uiwidget_creator.mutex);
+
+  // The GUI has sent a signal and the thread has been awakened.
 
-  // The GUI has sent a signal and the process has been awakened.
-  return uiwidget_creator.get_dialog_button ().toStdString ();
+  std::string answer = uiwidget_creator.get_dialog_button ().toStdString ();
+
+  uiwidget_creator.mutex.unlock ();
+
+  return answer;
 }
 
 static QStringList
@@ -232,6 +265,9 @@
                                 const std::string& ok_string,
                                 const std::string& cancel_string)
 {
+  // Lock mutex before signaling.
+  uiwidget_creator.mutex.lock ();
+
   uiwidget_creator.signal_listview (make_qstring_list (list),
                                     QString::fromStdString (mode),
                                     width, height,
@@ -242,12 +278,15 @@
                                     QString::fromStdString (cancel_string));
 
   // Wait while the user is responding to message box.
-  uiwidget_creator.wait ();
+  uiwidget_creator.waitcondition.wait (&uiwidget_creator.mutex);
 
-  // The GUI has sent a signal and the process has been awakened.
+  // The GUI has sent a signal and the thread has been awakened.
+
   const QIntList *selected = uiwidget_creator.get_list_index ();
   int ok = uiwidget_creator.get_dialog_result ();
 
+  uiwidget_creator.mutex.unlock ();
+
   return std::pair<std::list<int>, int> (selected->toStdList (), ok);
 }
 
@@ -260,6 +299,9 @@
 {
   std::list<std::string> retval;
 
+  // Lock mutex before signaling.
+  uiwidget_creator.mutex.lock ();
+
   uiwidget_creator.signal_inputlayout (make_qstring_list (prompt),
                                        QString::fromStdString (title),
                                        QFloatList::fromStdList (nr),
@@ -267,11 +309,14 @@
                                        make_qstring_list (defaults));
 
   // Wait while the user is responding to message box.
-  uiwidget_creator.wait ();
+  uiwidget_creator.waitcondition.wait (&uiwidget_creator.mutex);
+
+  // The GUI has sent a signal and the thread has been awakened.
 
-  // The GUI has sent a signal and the process has been awakened.
   const QStringList *inputLine = uiwidget_creator.get_string_list ();
 
+  uiwidget_creator.mutex.unlock ();
+
   for (QStringList::const_iterator it = inputLine->begin ();
        it != inputLine->end (); it++)
     {
@@ -290,6 +335,9 @@
 {
   std::list<std::string> retval;
 
+  // Lock mutex before signaling.
+  uiwidget_creator.mutex.lock ();
+
   uiwidget_creator.signal_filedialog (make_filter_list (filter),
                                       QString::fromStdString (title),
                                       QString::fromStdString (filename),
@@ -297,7 +345,9 @@
                                       QString::fromStdString (multimode));
 
   // Wait while the user is responding to dialog.
-  uiwidget_creator.wait ();
+  uiwidget_creator.waitcondition.wait (&uiwidget_creator.mutex);
+
+  // The GUI has sent a signal and the thread has been awakened.
 
   // Add all the file dialog results to a string list.
   const QStringList *inputLine = uiwidget_creator.get_string_list ();
@@ -310,6 +360,8 @@
   retval.push_back ((QString ("%1").arg (
                        uiwidget_creator.get_dialog_result ())).toStdString ());
 
+  uiwidget_creator.mutex.unlock ();
+
   return retval;
 }
 
@@ -346,13 +398,20 @@
   btn << cancel_txt;
   role << "AcceptRole";
 
+  // Lock mutex before signaling.
+  uiwidget_creator.mutex.lock ();
+
   uiwidget_creator.signal_dialog (msg, title, "quest", btn, cancel_txt, role);
 
   // Wait while the user is responding to message box.
-  uiwidget_creator.wait ();
+  uiwidget_creator.waitcondition.wait (&uiwidget_creator.mutex);
+
+  // The GUI has sent a signal and the thread has been awakened.
 
   QString result = uiwidget_creator.get_dialog_button ();
 
+  uiwidget_creator.mutex.unlock ();
+
   if (result == cd_txt)
     retval = 1;
   else if (result == addpath_txt)