--- a/libinterp/corefcn/graphics-toolkit.cc	Thu Nov 21 17:34:04 2019 -0500
+++ b/libinterp/corefcn/graphics-toolkit.cc	Thu Nov 21 18:41:08 2019 -0500
@@ -28,24 +28,27 @@
 #include "gtk-manager.h"
 #include "interpreter-private.h"
 
-void
-base_graphics_toolkit::update (const graphics_handle& h, int id)
+namespace octave
 {
-  gh_manager& gh_mgr
-    = octave::__get_gh_manager__ ("base_graphics_toolkit::update");
+  void
+  base_graphics_toolkit::update (const graphics_handle& h, int id)
+  {
+    gh_manager& gh_mgr
+      = octave::__get_gh_manager__ ("base_graphics_toolkit::update");
 
-  graphics_object go = gh_mgr.get_object (h);
-
-  update (go, id);
-}
+    graphics_object go = gh_mgr.get_object (h);
 
-bool
-base_graphics_toolkit::initialize (const graphics_handle& h)
-{
-  gh_manager& gh_mgr
-    = octave::__get_gh_manager__ ("base_graphics_toolkit::initialize");
+    update (go, id);
+  }
 
-  graphics_object go = gh_mgr.get_object (h);
+  bool
+  base_graphics_toolkit::initialize (const graphics_handle& h)
+  {
+    gh_manager& gh_mgr
+      = octave::__get_gh_manager__ ("base_graphics_toolkit::initialize");
 
-  return initialize (go);
+    graphics_object go = gh_mgr.get_object (h);
+
+    return initialize (go);
+  }
 }

--- a/libinterp/corefcn/graphics-toolkit.h	Thu Nov 21 17:34:04 2019 -0500
+++ b/libinterp/corefcn/graphics-toolkit.h	Thu Nov 21 18:41:08 2019 -0500
@@ -36,246 +36,256 @@
 #include "graphics-handle.h"
 
 class graphics_object;
-class graphics_toolkit;
-
-class base_graphics_toolkit
-{
-public:
-
-  friend class graphics_toolkit;
-
-public:
-
-  base_graphics_toolkit (const std::string& nm)
-    : m_name (nm)
-  { }
-
-  virtual ~base_graphics_toolkit (void) = default;
-
-  std::string get_name (void) const
-  {
-    return m_name;
-  }
-
-  virtual bool is_valid (void) const
-  {
-    return false;
-  }
-
-  virtual void redraw_figure (const graphics_object&) const
-  {
-    gripe_if_tkit_invalid ("redraw_figure");
-  }
-
-  virtual void show_figure (const graphics_object&) const
-  {
-    gripe_if_tkit_invalid ("show_figure");
-  }
-
-  virtual void print_figure (const graphics_object&, const std::string&,
-                             const std::string&,
-                             const std::string& = "") const
-  {
-    gripe_if_tkit_invalid ("print_figure");
-  }
-
-  virtual uint8NDArray get_pixels (const graphics_object&) const
-  {
-    gripe_if_tkit_invalid ("get_pixels");
-    return uint8NDArray ();
-  }
-
-  virtual Matrix get_canvas_size (const graphics_handle&) const
-  {
-    gripe_if_tkit_invalid ("get_canvas_size");
-    return Matrix (1, 2, 0.0);
-  }
 
-  virtual double get_screen_resolution (void) const
-  {
-    gripe_if_tkit_invalid ("get_screen_resolution");
-    return 72.0;
-  }
-
-  virtual Matrix get_screen_size (void) const
-  {
-    gripe_if_tkit_invalid ("get_screen_size");
-    return Matrix (1, 2, 0.0);
-  }
-
-  virtual Matrix get_text_extent (const graphics_object&) const
-  {
-    gripe_if_tkit_invalid ("get_text_extent");
-    return Matrix ();
-  }
-
-  // Callback function executed when the given graphics object
-  // changes.  This allows the graphics toolkit to act on property
-  // changes if needed.
-  virtual void update (const graphics_object&, int)
-  {
-    gripe_if_tkit_invalid ("base_graphics_toolkit::update");
-  }
-
-  void update (const graphics_handle&, int);
+namespace octave
+{
+  class graphics_toolkit;
 
-  // Callback function executed when the given graphics object is
-  // created.  This allows the graphics toolkit to do toolkit-specific
-  // initializations for a newly created object.
-  virtual bool initialize (const graphics_object&)
-  {
-    gripe_if_tkit_invalid ("base_graphics_toolkit::initialize");
-    return false;
-  }
-
-  bool initialize (const graphics_handle&);
-
-  // Callback function executed just prior to deleting the given
-  // graphics object.  This allows the graphics toolkit to perform
-  // toolkit-specific cleanup operations before an object is deleted.
-  virtual void finalize (const graphics_object&)
-  {
-    gripe_if_tkit_invalid ("base_graphics_toolkit::finalize");
-  }
-
-  void finalize (const graphics_handle&);
-
-  // Close the graphics toolkit.
-  virtual void close (void)
-  {
-    gripe_if_tkit_invalid ("base_graphics_toolkit::close");
-  }
-
-private:
-
-  std::string m_name;
-
-private:
-
-  void gripe_if_tkit_invalid (const std::string& fname) const
+  class base_graphics_toolkit
   {
-    if (! is_valid ())
-      error ("%s: invalid graphics toolkit", fname.c_str ());
-  }
-};
+  public:
+
+    friend class graphics_toolkit;
+
+  public:
+
+    base_graphics_toolkit (const std::string& nm)
+      : m_name (nm)
+    { }
+
+    virtual ~base_graphics_toolkit (void) = default;
 
-class graphics_toolkit
-{
-public:
-  graphics_toolkit (const std::string& name = "unknown")
-    : m_rep (new base_graphics_toolkit (name))
-  { }
+    std::string get_name (void) const
+    {
+      return m_name;
+    }
+
+    virtual bool is_valid (void) const
+    {
+      return false;
+    }
+
+    virtual void redraw_figure (const graphics_object&) const
+    {
+      gripe_if_tkit_invalid ("redraw_figure");
+    }
 
-  // NEW_REP must be dynamically allocated.
-  graphics_toolkit (base_graphics_toolkit *new_rep)
-    : m_rep (std::shared_ptr<base_graphics_toolkit> (new_rep))
-  {
-    if (! m_rep)
-      error ("invalid graphics_toolkit!");
-  }
+    virtual void show_figure (const graphics_object&) const
+    {
+      gripe_if_tkit_invalid ("show_figure");
+    }
+
+    virtual void print_figure (const graphics_object&, const std::string&,
+                               const std::string&,
+                               const std::string& = "") const
+    {
+      gripe_if_tkit_invalid ("print_figure");
+    }
 
-  graphics_toolkit (const graphics_toolkit& b) = default;
+    virtual uint8NDArray get_pixels (const graphics_object&) const
+    {
+      gripe_if_tkit_invalid ("get_pixels");
+      return uint8NDArray ();
+    }
 
-  graphics_toolkit& operator = (const graphics_toolkit& b) = default;
+    virtual Matrix get_canvas_size (const graphics_handle&) const
+    {
+      gripe_if_tkit_invalid ("get_canvas_size");
+      return Matrix (1, 2, 0.0);
+    }
 
-  ~graphics_toolkit (void) = default;
+    virtual double get_screen_resolution (void) const
+    {
+      gripe_if_tkit_invalid ("get_screen_resolution");
+      return 72.0;
+    }
 
-  operator bool (void) const
-  {
-    return m_rep->is_valid ();
-  }
+    virtual Matrix get_screen_size (void) const
+    {
+      gripe_if_tkit_invalid ("get_screen_size");
+      return Matrix (1, 2, 0.0);
+    }
+
+    virtual Matrix get_text_extent (const graphics_object&) const
+    {
+      gripe_if_tkit_invalid ("get_text_extent");
+      return Matrix ();
+    }
 
-  std::string get_name (void) const
-  {
-    return m_rep->get_name ();
-  }
+    // Callback function executed when the given graphics object
+    // changes.  This allows the graphics toolkit to act on property
+    // changes if needed.
+    virtual void update (const graphics_object&, int)
+    {
+      gripe_if_tkit_invalid ("base_graphics_toolkit::update");
+    }
 
-  void redraw_figure (const graphics_object& go) const
-  {
-    m_rep->redraw_figure (go);
-  }
+    void update (const graphics_handle&, int);
+
+    // Callback function executed when the given graphics object is
+    // created.  This allows the graphics toolkit to do toolkit-specific
+    // initializations for a newly created object.
+    virtual bool initialize (const graphics_object&)
+    {
+      gripe_if_tkit_invalid ("base_graphics_toolkit::initialize");
+      return false;
+    }
 
-  void show_figure (const graphics_object& go) const
-  {
-    m_rep->show_figure (go);
-  }
+    bool initialize (const graphics_handle&);
+
+    // Callback function executed just prior to deleting the given
+    // graphics object.  This allows the graphics toolkit to perform
+    // toolkit-specific cleanup operations before an object is deleted.
+    virtual void finalize (const graphics_object&)
+    {
+      gripe_if_tkit_invalid ("base_graphics_toolkit::finalize");
+    }
+
+    void finalize (const graphics_handle&);
 
-  void print_figure (const graphics_object& go, const std::string& term,
-                     const std::string& file,
-                     const std::string& debug_file = "") const
-  {
-    m_rep->print_figure (go, term, file, debug_file);
-  }
+    // Close the graphics toolkit.
+    virtual void close (void)
+    {
+      gripe_if_tkit_invalid ("base_graphics_toolkit::close");
+    }
+
+  private:
+
+    std::string m_name;
 
-  uint8NDArray get_pixels (const graphics_object& go) const
-  {
-    return m_rep->get_pixels (go);
-  }
+  private:
 
-  Matrix get_canvas_size (const graphics_handle& fh) const
+    void gripe_if_tkit_invalid (const std::string& fname) const
+    {
+      if (! is_valid ())
+        error ("%s: invalid graphics toolkit", fname.c_str ());
+    }
+  };
+
+  class graphics_toolkit
   {
-    return m_rep->get_canvas_size (fh);
-  }
+  public:
+    graphics_toolkit (const std::string& name = "unknown")
+      : m_rep (new base_graphics_toolkit (name))
+    { }
+
+    // NEW_REP must be dynamically allocated.
+    graphics_toolkit (base_graphics_toolkit *new_rep)
+      : m_rep (std::shared_ptr<base_graphics_toolkit> (new_rep))
+    {
+      if (! m_rep)
+        error ("invalid graphics_toolkit!");
+    }
 
-  double get_screen_resolution (void) const
-  {
-    return m_rep->get_screen_resolution ();
-  }
+    graphics_toolkit (const graphics_toolkit& b) = default;
+
+    graphics_toolkit& operator = (const graphics_toolkit& b) = default;
+
+    ~graphics_toolkit (void) = default;
 
-  Matrix get_screen_size (void) const
-  {
-    return m_rep->get_screen_size ();
-  }
+    operator bool (void) const
+    {
+      return m_rep->is_valid ();
+    }
+
+    std::string get_name (void) const
+    {
+      return m_rep->get_name ();
+    }
 
-  Matrix get_text_extent (const graphics_object& go) const
-  {
-    return m_rep->get_text_extent (go);
-  }
+    void redraw_figure (const graphics_object& go) const
+    {
+      m_rep->redraw_figure (go);
+    }
+
+    void show_figure (const graphics_object& go) const
+    {
+      m_rep->show_figure (go);
+    }
 
-  // Notifies graphics toolkit that object't property has changed.
-  void update (const graphics_object& go, int id)
-  {
-    m_rep->update (go, id);
-  }
+    void print_figure (const graphics_object& go, const std::string& term,
+                       const std::string& file,
+                       const std::string& debug_file = "") const
+    {
+      m_rep->print_figure (go, term, file, debug_file);
+    }
 
-  void update (const graphics_handle& h, int id)
-  {
-    m_rep->update (h, id);
-  }
+    uint8NDArray get_pixels (const graphics_object& go) const
+    {
+      return m_rep->get_pixels (go);
+    }
+
+    Matrix get_canvas_size (const graphics_handle& fh) const
+    {
+      return m_rep->get_canvas_size (fh);
+    }
+
+    double get_screen_resolution (void) const
+    {
+      return m_rep->get_screen_resolution ();
+    }
 
-  // Notifies graphics toolkit that new object was created.
-  bool initialize (const graphics_object& go)
-  {
-    return m_rep->initialize (go);
-  }
+    Matrix get_screen_size (void) const
+    {
+      return m_rep->get_screen_size ();
+    }
+
+    Matrix get_text_extent (const graphics_object& go) const
+    {
+      return m_rep->get_text_extent (go);
+    }
 
-  bool initialize (const graphics_handle& h)
-  {
-    return m_rep->initialize (h);
-  }
+    // Notifies graphics toolkit that object't property has changed.
+    void update (const graphics_object& go, int id)
+    {
+      m_rep->update (go, id);
+    }
+
+    void update (const graphics_handle& h, int id)
+    {
+      m_rep->update (h, id);
+    }
+
+    // Notifies graphics toolkit that new object was created.
+    bool initialize (const graphics_object& go)
+    {
+      return m_rep->initialize (go);
+    }
 
-  // Notifies graphics toolkit that object was destroyed.
-  // This is called only for explicitly deleted object.
-  // Children are deleted implicitly and graphics toolkit isn't notified.
-  void finalize (const graphics_object& go)
-  {
-    m_rep->finalize (go);
-  }
+    bool initialize (const graphics_handle& h)
+    {
+      return m_rep->initialize (h);
+    }
+
+    // Notifies graphics toolkit that object was destroyed.
+    // This is called only for explicitly deleted object.
+    // Children are deleted implicitly and graphics toolkit isn't notified.
+    void finalize (const graphics_object& go)
+    {
+      m_rep->finalize (go);
+    }
+
+    void finalize (const graphics_handle& h)
+    {
+      m_rep->finalize (h);
+    }
 
-  void finalize (const graphics_handle& h)
-  {
-    m_rep->finalize (h);
-  }
+    // Close the graphics toolkit.
+    void close (void)
+    {
+      m_rep->close ();
+    }
+
+  private:
 
-  // Close the graphics toolkit.
-  void close (void)
-  {
-    m_rep->close ();
-  }
+    std::shared_ptr<base_graphics_toolkit> m_rep;
+  };
+}
 
-private:
+OCTAVE_DEPRECATED (6, "use 'octave::graphics_toolkit' instead")
+typedef octave::graphics_toolkit graphics_toolkit;
 
-  std::shared_ptr<base_graphics_toolkit> m_rep;
-};
+OCTAVE_DEPRECATED (6, "use 'octave::base_graphics_toolkit' instead")
+typedef octave::base_graphics_toolkit base_graphics_toolkit;
 
 #endif

--- a/libinterp/corefcn/graphics.cc	Thu Nov 21 17:34:04 2019 -0500
+++ b/libinterp/corefcn/graphics.cc	Thu Nov 21 18:41:08 2019 -0500
@@ -2122,7 +2122,7 @@
 }
 
 void
-figure::properties::set_toolkit (const graphics_toolkit& b)
+figure::properties::set_toolkit (const octave::graphics_toolkit& b)
 {
   if (toolkit)
     finalize_r (get___myhandle__ ());
@@ -3515,7 +3515,7 @@
           || (! executing_callbacks.empty () && ! handlevisibility.is ("off")));
 }
 
-graphics_toolkit
+octave::graphics_toolkit
 base_properties::get_toolkit (void) const
 {
   gh_manager& gh_mgr
@@ -3526,7 +3526,7 @@
   if (go)
     return go.get_toolkit ();
   else
-    return graphics_toolkit ();
+    return octave::graphics_toolkit ();
 }
 
 void
@@ -4182,7 +4182,7 @@
     return Matrix ();
 }
 
-graphics_toolkit
+octave::graphics_toolkit
 figure::properties::get_toolkit (void) const
 {
   return toolkit;
@@ -4199,7 +4199,7 @@
   octave::gtk_manager& gtk_mgr
     = octave::__get_gtk_manager__ ("figure::properties::set___graphics_toolkit__");
 
-  graphics_toolkit b = gtk_mgr.find_toolkit (nm);
+  octave::graphics_toolkit b = gtk_mgr.find_toolkit (nm);
 
   if (b.get_name () != nm)
     error ("set___graphics_toolkit__: invalid graphics toolkit");

--- a/libinterp/corefcn/graphics.in.h	Thu Nov 21 17:34:04 2019 -0500
+++ b/libinterp/corefcn/graphics.in.h	Thu Nov 21 18:41:08 2019 -0500
@@ -2255,7 +2255,7 @@
     mark_modified ();
   }
 
-  virtual graphics_toolkit get_toolkit (void) const;
+  virtual octave::graphics_toolkit get_toolkit (void) const;
 
   virtual Matrix
   get_boundingbox (bool /* finternal */ = false,
@@ -2619,7 +2619,7 @@
     return type () == go_name;
   }
 
-  virtual graphics_toolkit get_toolkit (void) const
+  virtual octave::graphics_toolkit get_toolkit (void) const
   {
     if (! valid_object ())
       error ("base_graphics_object::get_toolkit: invalid graphics object");
@@ -2866,7 +2866,7 @@
   bool is_handle_visible (void) const
   { return get_properties ().is_handle_visible (); }
 
-  graphics_toolkit get_toolkit (void) const { return rep->get_toolkit (); }
+  octave::graphics_toolkit get_toolkit (void) const { return rep->get_toolkit (); }
 
   void add_property_listener (const std::string& nm, const octave_value& v,
                               listener_mode mode = GCB_POSTSET)
@@ -3087,9 +3087,9 @@
 
     void set_visible (const octave_value& val);
 
-    graphics_toolkit get_toolkit (void) const;
-
-    void set_toolkit (const graphics_toolkit& b);
+    octave::graphics_toolkit get_toolkit (void) const;
+
+    void set_toolkit (const octave::graphics_toolkit& b);
 
     void set___graphics_toolkit__ (const octave_value& val);
 
@@ -3233,7 +3233,7 @@
 
     void init_toolkit (void);
 
-    graphics_toolkit toolkit;
+    octave::graphics_toolkit toolkit;
   };
 
 private:

--- a/libinterp/dldfcn/__init_fltk__.cc	Thu Nov 21 17:34:04 2019 -0500
+++ b/libinterp/dldfcn/__init_fltk__.cc	Thu Nov 21 18:41:08 2019 -0500
@@ -2255,12 +2255,12 @@
 
 static bool toolkit_loaded = false;
 
-class fltk_graphics_toolkit : public base_graphics_toolkit
+class fltk_graphics_toolkit : public octave::base_graphics_toolkit
 {
 public:
 
   fltk_graphics_toolkit (octave::interpreter& interp)
-    : base_graphics_toolkit (FLTK_GRAPHICS_TOOLKIT_NAME),
+    : octave::base_graphics_toolkit (FLTK_GRAPHICS_TOOLKIT_NAME),
       m_interpreter (interp), input_event_hook_fcn_id ()
   {
     Fl::visual (FL_RGB);
@@ -2522,7 +2522,7 @@
       octave::gtk_manager& gtk_mgr = interp.get_gtk_manager ();
 
       fltk_graphics_toolkit *fltk = new fltk_graphics_toolkit (interp);
-      graphics_toolkit tk (fltk);
+      octave::graphics_toolkit tk (fltk);
       gtk_mgr.load_toolkit (tk);
       toolkit_loaded = true;
 

--- a/libinterp/dldfcn/__init_gnuplot__.cc	Thu Nov 21 17:34:04 2019 -0500
+++ b/libinterp/dldfcn/__init_gnuplot__.cc	Thu Nov 21 18:41:08 2019 -0500
@@ -54,11 +54,11 @@
 
 static bool toolkit_loaded = false;
 
-class gnuplot_graphics_toolkit : public base_graphics_toolkit
+class gnuplot_graphics_toolkit : public octave::base_graphics_toolkit
 {
 public:
   gnuplot_graphics_toolkit (octave::interpreter& interp)
-    : base_graphics_toolkit ("gnuplot"), m_interpreter (interp) { }
+    : octave::base_graphics_toolkit ("gnuplot"), m_interpreter (interp) { }
 
   ~gnuplot_graphics_toolkit (void) = default;
 
@@ -237,7 +237,7 @@
 
       octave::gtk_manager& gtk_mgr = interp.get_gtk_manager ();
 
-      graphics_toolkit tk (new gnuplot_graphics_toolkit (interp));
+      octave::graphics_toolkit tk (new gnuplot_graphics_toolkit (interp));
       gtk_mgr.load_toolkit (tk);
 
       toolkit_loaded = true;