--- a/libgui/src/dialog.cc	Wed Sep 06 13:56:50 2017 -0400
+++ b/libgui/src/dialog.cc	Wed Sep 06 15:00:52 2017 -0400
@@ -61,7 +61,7 @@
 QUIWidgetCreator::dialog_button_clicked (QAbstractButton *button)
 {
   // Wait for link thread to go to sleep state.
-  mutex.lock ();
+  lock ();
 
   // Store the value so that builtin functions can retrieve.
   if (button)
@@ -70,10 +70,10 @@
   // The value should always be 1 for the Octave functions.
   m_dialog_result = 1;
 
-  mutex.unlock ();
+  unlock ();
 
   // Wake up Octave process so that it continues.
-  waitcondition.wakeAll ();
+  wake_all ();
 }
 
 void
@@ -81,32 +81,32 @@
                                         int button_pressed)
 {
   // Wait for link thread to go to sleep state.
-  mutex.lock ();
+  lock ();
 
   // Store the value so that builtin functions can retrieve.
   *m_list_index = selected;
   m_dialog_result = button_pressed;
 
-  mutex.unlock ();
+  unlock ();
 
   // Wake up Octave process so that it continues.
-  waitcondition.wakeAll ();
+  wake_all ();
 }
 
 void
 QUIWidgetCreator::input_finished (const QStringList& input, int button_pressed)
 {
   // Wait for link thread to go to sleep state.
-  mutex.lock ();
+  lock ();
 
   // Store the value so that builtin functions can retrieve.
   *m_string_list = input;
   m_dialog_result = button_pressed;
 
-  mutex.unlock ();
+  unlock ();
 
   // Wake up Octave process so that it continues.
-  waitcondition.wakeAll ();
+  wake_all ();
 }
 
 void
@@ -114,17 +114,17 @@
                                        const QString& path, int filterindex)
 {
   // Wait for link thread to go to sleep state.
-  mutex.lock ();
+  lock ();
 
   // Store the value so that builtin functions can retrieve.
   *m_string_list = files;
   m_dialog_result = filterindex;
   *m_path_name = path;
 
-  mutex.unlock ();
+  unlock ();
 
   // Wake up Octave process so that it continues.
-  waitcondition.wakeAll ();
+  wake_all ();
 }
 
 MessageDialog::MessageDialog (const QString& message,

--- a/libgui/src/dialog.h	Wed Sep 06 13:56:50 2017 -0400
+++ b/libgui/src/dialog.h	Wed Sep 06 15:00:52 2017 -0400
@@ -114,11 +114,10 @@
 
   const QString * get_dialog_path (void) { return m_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;
+  void lock (void) { m_mutex.lock (); }
+  void wait (void) { m_waitcondition.wait (&m_mutex); }
+  void unlock (void) { m_mutex.unlock (); }
+  void wake_all (void) { m_waitcondition.wakeAll (); }
 
 signals:
 
@@ -158,6 +157,12 @@
   QIntList *m_list_index;
 
   QString *m_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 m_mutex;
+  QWaitCondition m_waitcondition;
 };
 
 extern QUIWidgetCreator uiwidget_creator;

--- a/libgui/src/main-window.cc	Wed Sep 06 13:56:50 2017 -0400
+++ b/libgui/src/main-window.cc	Wed Sep 06 15:00:52 2017 -0400
@@ -937,15 +937,14 @@
     }
 
   // Wait for link thread to go to sleep state.
-  _octave_qt_link->mutex.lock ();
+  _octave_qt_link->lock ();
 
   _octave_qt_link->shutdown_confirmation (closenow);
 
-  _octave_qt_link->mutex.unlock ();
+  _octave_qt_link->unlock ();
 
   // Awake the worker thread so that it continues shutting down (or not).
-  _octave_qt_link->waitcondition.wakeAll ();
-
+  _octave_qt_link->wake_all ();
 }
 
 void

--- a/libgui/src/octave-qt-link.cc	Wed Sep 06 13:56:50 2017 -0400
+++ b/libgui/src/octave-qt-link.cc	Wed Sep 06 15:00:52 2017 -0400
@@ -58,16 +58,16 @@
 octave_qt_link::do_confirm_shutdown (void)
 {
   // Lock the mutex before emitting signal.
-  mutex.lock ();
+  lock ();
 
   emit confirm_shutdown_signal ();
 
   // Wait while the GUI shuts down.
-  waitcondition.wait (&mutex);
+  wait ();
 
   // The GUI has sent a signal and the thread has been awakened.
 
-  mutex.unlock ();
+  unlock ();
 
   return m_shutdown_confirm_result;
 }
@@ -103,7 +103,7 @@
   btn << tr ("Create") << tr ("Cancel");
 
   // Lock mutex before signaling.
-  uiwidget_creator.mutex.lock ();
+  uiwidget_creator.lock ();
 
   uiwidget_creator.signal_dialog (
     tr ("File\n%1\ndoes not exist. Do you want to create it?").
@@ -112,13 +112,13 @@
     tr ("Octave Editor"), "quest", btn, tr ("Create"), role);
 
   // Wait while the user is responding to message box.
-  uiwidget_creator.waitcondition.wait (&uiwidget_creator.mutex);
+  uiwidget_creator.wait ();
 
   // The GUI has sent a signal and the thread has been awakened.
 
   QString answer = uiwidget_creator.get_dialog_button ();
 
-  uiwidget_creator.mutex.unlock ();
+  uiwidget_creator.unlock ();
 
   return (answer == tr ("Create"));
 }
@@ -129,7 +129,7 @@
                                    const std::string& title)
 {
   // Lock mutex before signaling.
-  uiwidget_creator.mutex.lock ();
+  uiwidget_creator.lock ();
 
   uiwidget_creator.signal_dialog (QString::fromStdString (msg),
                                   QString::fromStdString (title),
@@ -138,13 +138,13 @@
                                   QStringList ());
 
   // Wait while the user is responding to message box.
-  uiwidget_creator.waitcondition.wait (&uiwidget_creator.mutex);
+  uiwidget_creator.wait ();
 
   // The GUI has sent a signal and the thread has been awakened.
 
   int answer = uiwidget_creator.get_dialog_result ();
 
-  uiwidget_creator.mutex.unlock ();
+  uiwidget_creator.unlock ();
 
   return answer;
 }
@@ -169,7 +169,7 @@
   btn << QString::fromStdString (btn3);
 
   // Lock mutex before signaling.
-  uiwidget_creator.mutex.lock ();
+  uiwidget_creator.lock ();
 
   uiwidget_creator.signal_dialog (QString::fromStdString (msg),
                                   QString::fromStdString (title),
@@ -179,13 +179,13 @@
                                   role);
 
   // Wait while the user is responding to message box.
-  uiwidget_creator.waitcondition.wait (&uiwidget_creator.mutex);
+  uiwidget_creator.wait ();
 
   // The GUI has sent a signal and the thread has been awakened.
 
   std::string answer = uiwidget_creator.get_dialog_button ().toStdString ();
 
-  uiwidget_creator.mutex.unlock ();
+  uiwidget_creator.unlock ();
 
   return answer;
 }
@@ -249,7 +249,7 @@
                                 const std::string& cancel_string)
 {
   // Lock mutex before signaling.
-  uiwidget_creator.mutex.lock ();
+  uiwidget_creator.lock ();
 
   uiwidget_creator.signal_listview (make_qstring_list (list),
                                     QString::fromStdString (mode),
@@ -261,14 +261,14 @@
                                     QString::fromStdString (cancel_string));
 
   // Wait while the user is responding to message box.
-  uiwidget_creator.waitcondition.wait (&uiwidget_creator.mutex);
+  uiwidget_creator.wait ();
 
   // 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 ();
+  uiwidget_creator.unlock ();
 
   return std::pair<std::list<int>, int> (selected->toStdList (), ok);
 }
@@ -283,7 +283,7 @@
   std::list<std::string> retval;
 
   // Lock mutex before signaling.
-  uiwidget_creator.mutex.lock ();
+  uiwidget_creator.lock ();
 
   uiwidget_creator.signal_inputlayout (make_qstring_list (prompt),
                                        QString::fromStdString (title),
@@ -292,13 +292,13 @@
                                        make_qstring_list (defaults));
 
   // Wait while the user is responding to message box.
-  uiwidget_creator.waitcondition.wait (&uiwidget_creator.mutex);
+  uiwidget_creator.wait ();
 
   // The GUI has sent a signal and the thread has been awakened.
 
   const QStringList *inputLine = uiwidget_creator.get_string_list ();
 
-  uiwidget_creator.mutex.unlock ();
+  uiwidget_creator.unlock ();
 
   for (QStringList::const_iterator it = inputLine->begin ();
        it != inputLine->end (); it++)
@@ -319,7 +319,7 @@
   std::list<std::string> retval;
 
   // Lock mutex before signaling.
-  uiwidget_creator.mutex.lock ();
+  uiwidget_creator.lock ();
 
   uiwidget_creator.signal_filedialog (make_filter_list (filter),
                                       QString::fromStdString (title),
@@ -328,7 +328,7 @@
                                       QString::fromStdString (multimode));
 
   // Wait while the user is responding to dialog.
-  uiwidget_creator.waitcondition.wait (&uiwidget_creator.mutex);
+  uiwidget_creator.wait ();
 
   // The GUI has sent a signal and the thread has been awakened.
 
@@ -343,7 +343,7 @@
   retval.push_back ((QString ("%1").arg (
                        uiwidget_creator.get_dialog_result ())).toStdString ());
 
-  uiwidget_creator.mutex.unlock ();
+  uiwidget_creator.unlock ();
 
   return retval;
 }
@@ -386,18 +386,18 @@
   role << "RejectRole";
 
   // Lock mutex before signaling.
-  uiwidget_creator.mutex.lock ();
+  uiwidget_creator.lock ();
 
   uiwidget_creator.signal_dialog (msg, title, "quest", btn, cancel_txt, role);
 
   // Wait while the user is responding to message box.
-  uiwidget_creator.waitcondition.wait (&uiwidget_creator.mutex);
+  uiwidget_creator.wait ();
 
   // The GUI has sent a signal and the thread has been awakened.
 
   QString result = uiwidget_creator.get_dialog_button ();
 
-  uiwidget_creator.mutex.unlock ();
+  uiwidget_creator.unlock ();
 
   if (result == cd_txt)
     retval = 1;

--- a/libgui/src/octave-qt-link.h	Wed Sep 06 13:56:50 2017 -0400
+++ b/libgui/src/octave-qt-link.h	Wed Sep 06 15:00:52 2017 -0400
@@ -145,8 +145,10 @@
 
   void shutdown_confirmation (bool sd) { m_shutdown_confirm_result = sd; }
 
-  QMutex mutex;
-  QWaitCondition waitcondition;
+  void lock (void) { m_mutex.lock (); }
+  void wait (void) { m_waitcondition.wait (&m_mutex); }
+  void unlock (void) { m_mutex.unlock (); }
+  void wake_all (void) { m_waitcondition.wakeAll (); }
 
 private:
 
@@ -160,6 +162,9 @@
   QString m_current_directory;
   bool m_new_dir;
 
+  QMutex m_mutex;
+  QWaitCondition m_waitcondition;
+
 signals:
 
   void copy_image_to_clipboard_signal (const QString& file, bool remove_file);