diff -r d56511a02884 src/graphics.cc
--- a/src/graphics.cc	Thu Jun 26 16:06:14 2008 -0400
+++ b/src/graphics.cc	Fri Jul 04 23:08:53 2008 +0200
@@ -1268,6 +1268,56 @@ gh_manager::do_free (const graphics_hand
 	error ("graphics_handle::free: can't delete root figure");
     }
 }
+#if defined (__WIN32__) && ! defined (__CYGWIN__)
+CRITICAL_SECTION __go_lock__;
+#else
+pthread_mutex_t __go_lock__;
+#endif
+
+void
+gh_manager::init_mutex (void)
+{
+#if defined (__WIN32__) && ! defined (__CYGWIN__)
+    InitializeCriticalSection (&__go_lock__);
+#else
+    pthread_mutexattr_t attr;
+    pthread_mutexattr_init (&attr);
+    pthread_mutexattr_settype (&attr, PTHREAD_MUTEX_RECURSIVE); // mutex needs to be recursive
+    pthread_mutex_init (&__go_lock__, &attr);
+    pthread_mutexattr_destroy (&attr);
+#endif
+}
+
+void
+gh_manager::cleanup_mutex (void)
+{
+#if defined (__WIN32__) && ! defined (__CYGWIN__)
+    DeleteCriticalSection (&__go_lock__);
+#else
+    pthread_mutex_destroy (&__go_lock__);
+#endif
+}
+
+void
+gh_manager::do_lock (void)
+{
+#if defined (__WIN32__) && ! defined (__CYGWIN__)
+  EnterCriticalSection (&__go_lock__);
+#else
+  pthread_mutex_lock (&__go_lock__);
+#endif
+}
+
+void
+gh_manager::do_unlock (void)
+{
+#if defined (__WIN32__) && ! defined (__CYGWIN__)
+  LeaveCriticalSection (&__go_lock__);
+#else
+  pthread_mutex_unlock (&__go_lock__); 
+#endif
+}
+
 
 gh_manager *gh_manager::instance = 0;
 
@@ -1275,6 +1325,8 @@ xset (const graphics_handle& h, const ca
 xset (const graphics_handle& h, const caseless_str& name,
       const octave_value& val)
 {
+  gh_manager::lock_guard guard;
+  
   graphics_object obj = gh_manager::get_object (h);
   obj.set (name, val);
 }
@@ -1282,6 +1334,8 @@ static void
 static void
 xset (const graphics_handle& h, const octave_value_list& args)
 {
+  gh_manager::lock_guard guard;
+  
   if (args.length () > 0)
     {
       graphics_object obj = gh_manager::get_object (h);
@@ -1293,6 +1347,8 @@ static octave_value
 static octave_value
 xget (const graphics_handle& h, const caseless_str& name)
 {
+  gh_manager::lock_guard guard;
+  
   graphics_object obj = gh_manager::get_object (h);
   return obj.get (name);
 }
@@ -1302,6 +1358,8 @@ reparent (const octave_value& ov, const 
 	  const std::string& property, const graphics_handle& new_parent,
 	  bool adopt = true)
 {
+  gh_manager::lock_guard guard;
+  
   graphics_handle h = octave_NaN;
 
   double val = ov.double_value ();
@@ -1357,6 +1415,8 @@ static void
 static void
 adopt (const graphics_handle& p, const graphics_handle& h)
 {
+  gh_manager::lock_guard guard;
+  
   graphics_object parent_obj = gh_manager::get_object (p);
 
   parent_obj.adopt (h);
@@ -1365,12 +1425,16 @@ static bool
 static bool
 is_handle (const graphics_handle& h)
 {
+  gh_manager::lock_guard guard;
+  
   return h.ok ();
 }
 
 static bool
 is_handle (double val)
 {
+  gh_manager::lock_guard guard;
+  
   graphics_handle h = gh_manager::lookup (val);
 
   return h.ok ();
@@ -1379,12 +1443,16 @@ static bool
 static bool
 is_handle (const octave_value& val)
 {
+  gh_manager::lock_guard guard;
+  
   return val.is_real_scalar () && is_handle (val.double_value ());
 }
 
 static bool
 is_figure (double val)
 {
+  gh_manager::lock_guard guard;
+  
   graphics_object obj = gh_manager::get_object (val);
 
   return obj && obj.isa ("figure");
@@ -1393,6 +1461,8 @@ static void
 static void
 xcreatefcn (const graphics_handle& h)
 {
+  gh_manager::lock_guard guard;
+  
   graphics_object obj = gh_manager::get_object (h);
   obj.get_properties ().execute_createfcn  ();
 }
@@ -1446,6 +1516,8 @@ base_properties::set_from_list (base_gra
 base_properties::set_from_list (base_graphics_object& obj,
 				property_list& defaults)
 {
+  gh_manager::lock_guard guard;
+  
   std::string go_name = graphics_object_name ();
 
   property_list::plist_map_const_iterator p = defaults.find (go_name);
@@ -1474,6 +1546,8 @@ octave_value
 octave_value
 base_properties::get (const caseless_str& name) const
 {
+  gh_manager::lock_guard guard;
+  
   octave_value retval;
 
   if (name.compare ("tag"))
@@ -1530,6 +1604,8 @@ octave_value
 octave_value
 base_properties::get (bool all) const
 {
+  gh_manager::lock_guard guard;
+  
   Octave_map m;
 
   for (std::map<caseless_str, property>::const_iterator it = all_props.begin ();
@@ -1564,6 +1640,8 @@ void
 void
 base_properties::set (const caseless_str& name, const octave_value& val)
 {
+  gh_manager::lock_guard guard;
+  
   if (name.compare ("tag"))
     set_tag (val);
   else if (name.compare ("__modified__"))
@@ -1685,6 +1763,8 @@ void
 void
 base_properties::remove_child (const graphics_handle& h)
 {
+  gh_manager::lock_guard guard;
+  
   octave_idx_type k = -1;
   octave_idx_type n = children.numel ();
   for (octave_idx_type i = 0; i < n; i++)
@@ -1713,6 +1793,8 @@ void
 void
 base_properties::set_parent (const octave_value& val)
 {
+  gh_manager::lock_guard guard;
+  
   double tmp = val.double_value ();
 
   graphics_handle new_parent = octave_NaN;
@@ -1759,6 +1841,8 @@ void
 void
 base_properties::update_axis_limits (const std::string& axis_type) const
 {
+  gh_manager::lock_guard guard;
+  
   graphics_object obj = gh_manager::get_object (__myhandle__);
 
   if (obj)
@@ -1768,6 +1852,8 @@ void
 void
 base_properties::delete_children (void)
 {
+  gh_manager::lock_guard guard;
+  
   octave_idx_type n = children.numel ();
 
   for (octave_idx_type i = 0; i < n; i++)
@@ -1788,6 +1874,8 @@ void
 void
 base_properties::update_boundingbox (void)
 {
+  gh_manager::lock_guard guard;
+  
   Matrix kids = get_children ();
 
   for (int i = 0; i < kids.numel (); i++)
@@ -1803,6 +1891,8 @@ base_properties::add_listener (const cas
 base_properties::add_listener (const caseless_str& nm, const octave_value& v,
 			       listener_mode mode)
 {
+  gh_manager::lock_guard guard;
+  
   property p = get_property (nm);
 
   if (! error_state && p.ok ())
@@ -1897,6 +1987,7 @@ base_graphics_object::update_axis_limits
 {
   if (valid_object ())
     {
+      gh_manager::lock_guard guard;
       graphics_object parent_obj = gh_manager::get_object (get_parent ());
 
       if (parent_obj)
@@ -1915,6 +2006,8 @@ void
 void
 root_figure::properties::set_currentfigure (const octave_value& v)
 {
+  gh_manager::lock_guard guard;
+  
   graphics_handle val (v);
 
   if (error_state)
@@ -1933,6 +2026,8 @@ void
 void
 root_figure::properties::set_callbackobject (const octave_value& v)
 {
+  gh_manager::lock_guard guard;
+  
   graphics_handle val (v);
 
   if (error_state)
@@ -1968,6 +2063,8 @@ void
 void
 figure::properties::set_currentaxes (const octave_value& v)
 {
+  gh_manager::lock_guard guard;
+  
   graphics_handle val (v);
 
   if (error_state)
@@ -2001,6 +2098,8 @@ figure::properties::close (bool pop)
 
   if (pop)
     {
+      gh_manager::lock_guard guard;
+
       gh_manager::pop_figure (__myhandle__);
 
       graphics_handle cf = gh_manager::current_figure ();
@@ -2012,6 +2111,8 @@ Matrix
 Matrix
 figure::properties::get_boundingbox (bool) const
 {
+  gh_manager::lock_guard guard;
+
   graphics_backend b = get_backend ();
   // FIXME: screen size should be obtained from root object
   Matrix screen_size = b.get_screen_size ();
@@ -2030,6 +2131,8 @@ void
 void
 figure::properties::set_boundingbox (const Matrix& bb)
 {
+  gh_manager::lock_guard guard;
+
   graphics_backend b = get_backend ();
   // FIXME: screen size should be obtained from root object
   Matrix screen_size = b.get_screen_size ();
@@ -2120,6 +2223,8 @@ void
 void
 axes::properties::set_title (const octave_value& v)
 {
+  gh_manager::lock_guard guard;
+  
   graphics_handle val = ::reparent (v, "set", "title", __myhandle__, false);
 
   if (! error_state)
@@ -2132,6 +2237,8 @@ void
 void
 axes::properties::set_xlabel (const octave_value& v)
 {
+  gh_manager::lock_guard guard;
+  
   graphics_handle val = ::reparent (v, "set", "xlabel", __myhandle__, false);
 
   if (! error_state)
@@ -2144,6 +2251,8 @@ void
 void
 axes::properties::set_ylabel (const octave_value& v)
 {
+  gh_manager::lock_guard guard;
+  
   graphics_handle val = ::reparent (v, "set", "ylabel", __myhandle__, false);
 
   if (! error_state)
@@ -2156,6 +2265,8 @@ void
 void
 axes::properties::set_zlabel (const octave_value& v)
 {
+  gh_manager::lock_guard guard;
+  
   graphics_handle val = ::reparent (v, "set", "zlabel", __myhandle__, false);
 
   if (! error_state)
@@ -2169,6 +2280,8 @@ axes::properties::set_defaults (base_gra
 axes::properties::set_defaults (base_graphics_object& obj,
 				const std::string& mode)
 {
+  gh_manager::lock_guard guard;
+
   title = graphics_handle ();
   box = "on";
   key = "off";
@@ -2290,6 +2403,8 @@ graphics_handle
 graphics_handle
 axes::properties::get_title (void) const
 {
+  gh_manager::lock_guard guard;
+
   if (! title.handle_value ().ok ())
     title = gh_manager::make_graphics_handle ("text", __myhandle__);
 
@@ -2299,6 +2414,8 @@ graphics_handle
 graphics_handle
 axes::properties::get_xlabel (void) const
 {
+  gh_manager::lock_guard guard;
+
   if (! xlabel.handle_value ().ok ())
     xlabel = gh_manager::make_graphics_handle ("text", __myhandle__);
 
@@ -2308,6 +2425,8 @@ graphics_handle
 graphics_handle
 axes::properties::get_ylabel (void) const
 {
+  gh_manager::lock_guard guard;
+
   if (! ylabel.handle_value ().ok ())
     ylabel = gh_manager::make_graphics_handle ("text", __myhandle__);
 
@@ -2317,6 +2436,8 @@ graphics_handle
 graphics_handle
 axes::properties::get_zlabel (void) const
 {
+  gh_manager::lock_guard guard;
+
   if (! zlabel.handle_value ().ok ())
     zlabel = gh_manager::make_graphics_handle ("text", __myhandle__);
 
@@ -2326,6 +2447,8 @@ void
 void
 axes::properties::remove_child (const graphics_handle& h)
 {
+  gh_manager::lock_guard guard;
+  
   if (title.handle_value ().ok () && h == title.handle_value ())
     title = gh_manager::make_graphics_handle ("text", __myhandle__);
   else if (xlabel.handle_value ().ok () && h == xlabel.handle_value ())
@@ -2341,6 +2464,8 @@ void
 void
 axes::properties::delete_children (void)
 {
+  gh_manager::lock_guard guard;
+  
   base_properties::delete_children ();
 
   gh_manager::free (title.handle_value ());
@@ -2493,6 +2618,8 @@ void
 void
 axes::properties::update_camera (void)
 {
+  gh_manager::lock_guard guard;
+  
   double xd = (xdir_is ("normal") ? 1 : -1);
   double yd = (ydir_is ("normal") ? 1 : -1);
   double zd = (zdir_is ("normal") ? 1 : -1);
@@ -2709,6 +2836,8 @@ void
 void
 axes::properties::update_aspectratios (void)
 {
+  gh_manager::lock_guard guard;
+
   Matrix xlimits = get_xlim ().matrix_value ();
   Matrix ylimits = get_ylim ().matrix_value ();
   Matrix zlimits = get_zlim ().matrix_value ();
@@ -2753,6 +2882,8 @@ Matrix
 Matrix
 axes::properties::get_boundingbox (bool internal) const
 {
+  gh_manager::lock_guard guard;
+
   graphics_object obj = gh_manager::get_object (get_parent ());
   Matrix parent_bb = obj.get_properties ().get_boundingbox (true);
   Matrix pos = (internal ?
@@ -2818,6 +2949,8 @@ axes::get_default (const caseless_str& n
 
   if (retval.is_undefined ())
     {
+      gh_manager::lock_guard guard;
+
       graphics_handle parent = get_parent ();
       graphics_object parent_obj = gh_manager::get_object (parent);
 
@@ -3071,6 +3204,8 @@ get_children_limits (double& min_val, do
 get_children_limits (double& min_val, double& max_val, double& min_pos,
 		     const Matrix& kids, char limit_type)
 {
+  gh_manager::lock_guard guard;
+
   octave_idx_type n = kids.numel ();
 
   switch (limit_type)
@@ -3418,6 +3553,8 @@ void
 void
 surface::properties::update_normals (void)
 {
+  gh_manager::lock_guard guard;
+
   if (normalmode_is ("auto"))
     {
       Matrix x = get_xdata ().matrix_value ();
@@ -3571,6 +3708,8 @@ octave_value
 octave_value
 base_graphics_object::get_default (const caseless_str& name) const
 {
+  gh_manager::lock_guard guard;
+
   graphics_handle parent = get_parent ();
   graphics_object parent_obj = gh_manager::get_object (parent);
 
@@ -3591,10 +3730,16 @@ gh_manager::gh_manager (void)
   : handle_map (), handle_free_list (),
     next_handle (-1.0 - (rand () + 1.0) / (RAND_MAX + 2.0))
 {
+  init_mutex();
   handle_map[0] = graphics_object (new root_figure ());
 
   // Make sure the default backend is registered.
   graphics_backend::default_backend ();
+}
+
+gh_manager::~gh_manager (void)
+{
+  cleanup_mutex ();
 }
 
 graphics_handle
@@ -3695,6 +3840,8 @@ for the graphics handle @var{h}.\n\
 for the graphics handle @var{h}.\n\
 @end deftypefn")
 {
+  gh_manager::lock_guard guard;
+
   octave_value retval;
 
   int nargin = args.length ();
@@ -3745,6 +3892,8 @@ values or lists respectively.\n\
 values or lists respectively.\n\
 @end deftypefn")
 {
+  gh_manager::lock_guard guard;
+
   octave_value retval;
   octave_value_list vlist;
 
@@ -3815,6 +3964,8 @@ values or lists respectively.\n\
 values or lists respectively.\n\
 @end deftypefn")
 {
+  gh_manager::lock_guard guard;
+
   octave_value retval;
   octave_value_list vlist;
 
@@ -3866,6 +4017,8 @@ make_graphics_object (const std::string&
 make_graphics_object (const std::string& go_name,
 		      const octave_value_list& args)
 {
+  gh_manager::lock_guard guard;
+
   octave_value retval;
 
   double val = octave_NaN;
@@ -3936,6 +4089,8 @@ Undocumented internal function.\n\
 Undocumented internal function.\n\
 @end deftypefn")
 {
+  gh_manager::lock_guard guard;
+
   octave_value retval;
 
   if (args.length () > 0)
@@ -4064,6 +4219,8 @@ Undocumented internal function.\n\
 Undocumented internal function.\n\
 @end deftypefn")
 {
+  gh_manager::lock_guard guard;
+
   octave_value_list retval;
 
   if (args.length () == 1)
@@ -4112,6 +4269,8 @@ Undocumented internal function.\n\
 Undocumented internal function.\n\
 @end deftypefn")
 {
+  gh_manager::lock_guard guard;
+
   octave_value retval;
 
   int nargin = args.length ();
@@ -4354,6 +4513,8 @@ addlistener (gcf, \"position\", @{@@my_l
 
 	      if (gh.ok ())
 		{
+		  gh_manager::lock_guard guard;
+
 		  graphics_object go = gh_manager::get_object (gh);
 
 		  go.add_property_listener (pname, args(2), POSTSET);
@@ -4446,6 +4607,8 @@ addproperty (\"my_style\", gcf, \"lineli
 
 	  if (! error_state)
 	    {
+	      gh_manager::lock_guard guard;
+
 	      graphics_handle gh = gh_manager::lookup (h);
 
 	      if (gh.ok ())
@@ -4490,6 +4653,8 @@ get_property_from_handle (double handle,
 get_property_from_handle (double handle, const std::string& property,
 			  const std::string& func)
 {
+  gh_manager::lock_guard guard;
+
   graphics_object obj = gh_manager::get_object (handle);
   octave_value retval;
 
@@ -4508,6 +4673,8 @@ set_property_in_handle (double handle, c
 set_property_in_handle (double handle, const std::string& property,
 			const octave_value& arg, const std::string& func)
 {
+  gh_manager::lock_guard guard;
+
   graphics_object obj = gh_manager::get_object (handle);
   int ret = false;
 
diff -r d56511a02884 src/graphics.h.in
--- a/src/graphics.h.in	Thu Jun 26 16:06:14 2008 -0400
+++ b/src/graphics.h.in	Fri Jul 04 23:08:53 2008 +0200
@@ -3486,6 +3486,8 @@ protected:
 
 public:
 
+  ~gh_manager (void);
+  
   static bool instance_ok (void)
   {
     bool retval = true;
@@ -3561,6 +3563,38 @@ public:
   {
     return instance_ok () ? instance->do_figure_handle_list () : Matrix ();
   }
+  
+  /// Locks gh_manager instance. Use to protect property access.
+  /// Locking is recursive, this method can be called multiple times, and a corresponding number of unlock() calls
+  /// is required in order to unlock mutex.
+  static void lock (void)
+  {
+  if (instance_ok ())
+      instance->do_lock ();
+  }
+
+  /// Unlocks gh_manager instance.
+  ///\see lock(void)
+  static void unlock (void)
+  {
+    if (instance_ok ())
+      instance->do_unlock ();
+  }
+
+  /// Lock guard object, allows for simple RIIA locking.
+  class lock_guard
+  {
+  public:
+    lock_guard (void)
+    {
+      lock();
+    }
+    
+    ~lock_guard (void)
+    {
+      unlock();
+    }
+  };
 
 private:
 
@@ -3645,6 +3679,14 @@ private:
   {
     return figure_list.empty () ? graphics_handle () : figure_list.front ();
   }
+  
+  void do_lock (void);
+  
+  void do_unlock (void);
+  
+  void init_mutex (void);
+  
+  void cleanup_mutex (void);
 };