diff -r d56511a02884 src/graphics.cc
--- a/src/graphics.cc	Thu Jun 26 16:06:14 2008 -0400
+++ b/src/graphics.cc	Sat Jul 05 17:30:56 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;
 
@@ -3591,10 +3641,16 @@ 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 +3751,8 @@ 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 +3803,8 @@ 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 +3875,8 @@ values or lists respectively.\n\
 values or lists respectively.\n\
 @end deftypefn")
 {
+  gh_manager::lock_guard guard;
+
   octave_value retval;
   octave_value_list vlist;
 
@@ -3936,6 +3998,8 @@ Undocumented internal function.\n\
 Undocumented internal function.\n\
 @end deftypefn")
 {
+  gh_manager::lock_guard guard;
+
   octave_value retval;
 
   if (args.length () > 0)
@@ -4064,6 +4128,8 @@ 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 +4178,8 @@ Undocumented internal function.\n\
 Undocumented internal function.\n\
 @end deftypefn")
 {
+  gh_manager::lock_guard guard;
+
   octave_value retval;
 
   int nargin = args.length ();
@@ -4338,6 +4406,7 @@ addlistener (gcf, \"position\", @{@@my_l
 \n\
 @end deftypefn")
 {
+  gh_manager::lock_guard guard;
   octave_value retval;
 
   if (args.length () == 3)
@@ -4354,6 +4423,7 @@ addlistener (gcf, \"position\", @{@@my_l
 
 	      if (gh.ok ())
 		{
+
 		  graphics_object go = gh_manager::get_object (gh);
 
 		  go.add_property_listener (pname, args(2), POSTSET);
@@ -4434,6 +4504,7 @@ addproperty (\"my_style\", gcf, \"lineli
 \n\
 @end deftypefn")
 {
+  gh_manager::lock_guard guard;
   octave_value retval;
 
   if (args.length () >= 3)
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	Sat Jul 05 17:30:56 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);
 };