diff --git a/moo/Makefile.in b/moo/Makefile.in
index 9e029b0..2105b34 100644
--- a/moo/Makefile.in
+++ b/moo/Makefile.in
@@ -355,6 +355,7 @@ pdfdir = @pdfdir@
 prefix = @prefix@
 program_transform_name = @program_transform_name@
 psdir = @psdir@
+runstatedir = @runstatedir@
 sbindir = @sbindir@
 sharedstatedir = @sharedstatedir@
 srcdir = @srcdir@
@@ -585,7 +586,7 @@ distdir: $(DISTFILES)
 	  ! -type d ! -perm -444 -exec $(install_sh) -c -m a+r {} {} \; \
 	|| chmod -R a+r "$(distdir)"
 dist-gzip: distdir
-	tardir=$(distdir) && $(am__tar) | eval GZIP= gzip $(GZIP_ENV) -c >$(distdir).tar.gz
+	tardir=$(distdir) && $(am__tar) | GZIP=$(GZIP_ENV) gzip -c >$(distdir).tar.gz
 	$(am__post_remove_distdir)
 
 dist-bzip2: distdir
@@ -611,7 +612,7 @@ dist-shar: distdir
 	@echo WARNING: "Support for shar distribution archives is" \
 	               "deprecated." >&2
 	@echo WARNING: "It will be removed altogether in Automake 2.0" >&2
-	shar $(distdir) | eval GZIP= gzip $(GZIP_ENV) -c >$(distdir).shar.gz
+	shar $(distdir) | GZIP=$(GZIP_ENV) gzip -c >$(distdir).shar.gz
 	$(am__post_remove_distdir)
 
 dist-zip: distdir
@@ -629,7 +630,7 @@ dist dist-all:
 distcheck: dist
 	case '$(DIST_ARCHIVES)' in \
 	*.tar.gz*) \
-	  eval GZIP= gzip $(GZIP_ENV) -dc $(distdir).tar.gz | $(am__untar) ;;\
+	  GZIP=$(GZIP_ENV) gzip -dc $(distdir).tar.gz | $(am__untar) ;;\
 	*.tar.bz2*) \
 	  bzip2 -dc $(distdir).tar.bz2 | $(am__untar) ;;\
 	*.tar.lz*) \
@@ -639,7 +640,7 @@ distcheck: dist
 	*.tar.Z*) \
 	  uncompress -c $(distdir).tar.Z | $(am__untar) ;;\
 	*.shar.gz*) \
-	  eval GZIP= gzip $(GZIP_ENV) -dc $(distdir).shar.gz | unshar ;;\
+	  GZIP=$(GZIP_ENV) gzip -dc $(distdir).shar.gz | unshar ;;\
 	*.zip*) \
 	  unzip $(distdir).zip ;;\
 	esac
diff --git a/moo/configure b/moo/configure
index 3014b96..d303ef0 100755
--- a/moo/configure
+++ b/moo/configure
@@ -791,6 +791,7 @@ infodir
 docdir
 oldincludedir
 includedir
+runstatedir
 localstatedir
 sharedstatedir
 sysconfdir
@@ -887,6 +888,7 @@ datadir='${datarootdir}'
 sysconfdir='${prefix}/etc'
 sharedstatedir='${prefix}/com'
 localstatedir='${prefix}/var'
+runstatedir='${localstatedir}/run'
 includedir='${prefix}/include'
 oldincludedir='/usr/include'
 docdir='${datarootdir}/doc/${PACKAGE_TARNAME}'
@@ -1139,6 +1141,15 @@ do
   | -silent | --silent | --silen | --sile | --sil)
     silent=yes ;;
 
+  -runstatedir | --runstatedir | --runstatedi | --runstated \
+  | --runstate | --runstat | --runsta | --runst | --runs \
+  | --run | --ru | --r)
+    ac_prev=runstatedir ;;
+  -runstatedir=* | --runstatedir=* | --runstatedi=* | --runstated=* \
+  | --runstate=* | --runstat=* | --runsta=* | --runst=* | --runs=* \
+  | --run=* | --ru=* | --r=*)
+    runstatedir=$ac_optarg ;;
+
   -sbindir | --sbindir | --sbindi | --sbind | --sbin | --sbi | --sb)
     ac_prev=sbindir ;;
   -sbindir=* | --sbindir=* | --sbindi=* | --sbind=* | --sbin=* \
@@ -1276,7 +1287,7 @@ fi
 for ac_var in	exec_prefix prefix bindir sbindir libexecdir datarootdir \
 		datadir sysconfdir sharedstatedir localstatedir includedir \
 		oldincludedir docdir infodir htmldir dvidir pdfdir psdir \
-		libdir localedir mandir
+		libdir localedir mandir runstatedir
 do
   eval ac_val=\$$ac_var
   # Remove trailing slashes.
@@ -1429,6 +1440,7 @@ Fine tuning of the installation directories:
   --sysconfdir=DIR        read-only single-machine data [PREFIX/etc]
   --sharedstatedir=DIR    modifiable architecture-independent data [PREFIX/com]
   --localstatedir=DIR     modifiable single-machine data [PREFIX/var]
+  --runstatedir=DIR       modifiable per-process data [LOCALSTATEDIR/run]
   --libdir=DIR            object code libraries [EPREFIX/lib]
   --includedir=DIR        C header files [PREFIX/include]
   --oldincludedir=DIR     C header files for non-gcc [/usr/include]
@@ -18372,6 +18384,18 @@ _ACEOF
 fi
 done
 
+for ac_func in sigaction signal
+do :
+  as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
+ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
+if eval test \"x\$"$as_ac_var"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_func" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+done
+
 for ac_func in snprintf _vsnprintf _vsnwprintf strerror_r
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -21039,6 +21063,11 @@ _ACEOF
 
 fi
 
+cat >>confdefs.h <<_ACEOF
+#define MOO_NSIG ${ax_cv_numvalof_NSIG}
+_ACEOF
+
+
 
 cat >>confdefs.h <<_ACEOF
 #define MOO_SIZEOF_STRUCT_SOCKADDR_IN ${ac_cv_sizeof_struct_sockaddr_in}
diff --git a/moo/configure.ac b/moo/configure.ac
index ea5be41..8695616 100644
--- a/moo/configure.ac
+++ b/moo/configure.ac
@@ -153,6 +153,7 @@ AC_CHECK_FUNCS([backtrace backtrace_symbols])
 AC_CHECK_FUNCS([makecontext swapcontext getcontext setcontext])
 AC_CHECK_FUNCS([clock_nanosleep nanosleep usleep])
 AC_CHECK_FUNCS([localtime_r gmtime_r])
+AC_CHECK_FUNCS([sigaction signal])
 AC_CHECK_FUNCS([snprintf _vsnprintf _vsnwprintf strerror_r])
 AC_CHECK_FUNCS([accept4 pipe2 epoll_create1])
 AC_CHECK_FUNCS([isatty mmap munmap])
@@ -587,6 +588,7 @@ if test ${ax_cv_numvalof_PATH_MAX} -gt 0
 then
 	AC_DEFINE_UNQUOTED(MOO_PATH_MAX, ${ax_cv_numvalof_PATH_MAX}, [PATH_MAX])
 fi
+AC_DEFINE_UNQUOTED(MOO_NSIG, ${ax_cv_numvalof_NSIG}, [NSIG])
 
 AC_DEFINE_UNQUOTED(MOO_SIZEOF_STRUCT_SOCKADDR_IN, ${ac_cv_sizeof_struct_sockaddr_in}, [sizeof(struct sockaddr_in)])
 AC_DEFINE_UNQUOTED(MOO_SIZEOF_STRUCT_SOCKADDR_IN6, ${ac_cv_sizeof_struct_sockaddr_in6}, [sizeof(struct sockaddr_in6)])
diff --git a/moo/lib/Makefile.in b/moo/lib/Makefile.in
index 57d7a04..ecf645b 100644
--- a/moo/lib/Makefile.in
+++ b/moo/lib/Makefile.in
@@ -404,6 +404,7 @@ pdfdir = @pdfdir@
 prefix = @prefix@
 program_transform_name = @program_transform_name@
 psdir = @psdir@
+runstatedir = @runstatedir@
 sbindir = @sbindir@
 sharedstatedir = @sharedstatedir@
 srcdir = @srcdir@
diff --git a/moo/lib/main.c b/moo/lib/main.c
index f1d4e3c..f5052a6 100644
--- a/moo/lib/main.c
+++ b/moo/lib/main.c
@@ -116,208 +116,8 @@ static MOO_INLINE void abort_moo (void)
 	if (g_moo) moo_abortstd (g_moo);
 }
 
-static MOO_INLINE void swproc_moo (void)
-{
-	if (g_moo) moo_switchprocess (g_moo);
-}
-
 /* ========================================================================= */
 
-#if defined(__DOS__) && (defined(_INTELC32_) || defined(__WATCOMC__))
-
-#if defined(_INTELC32_)
-static void (*prev_timer_intr_handler) (void);
-#else
-static void (__interrupt *prev_timer_intr_handler) (void);
-#endif
-
-#if defined(_INTELC32_)
-#pragma interrupt(timer_intr_handler)
-static void timer_intr_handler (void)
-#else
-static void __interrupt timer_intr_handler (void)
-#endif
-{
-	/*
-	_XSTACK *stk;
-	int r;
-	stk = (_XSTACK *)_get_stk_frame();
-	r = (unsigned short)stk_ptr->eax;   
-	*/
-
-	/* The timer interrupt (normally) occurs 18.2 times per second. */
-	swproc_moo ();
-	_chain_intr (prev_timer_intr_handler);
-}
-
-
-static void setup_tick (void)
-{
-	prev_timer_intr_handler = _dos_getvect (0x1C);
-	_dos_setvect (0x1C, timer_intr_handler);
-}
-
-static void cancel_tick (void)
-{
-	_dos_setvect (0x1C, prev_timer_intr_handler);
-}
-
-#elif defined(_WIN32)
-
-static HANDLE g_tick_timer = MOO_NULL; /*INVALID_HANDLE_VALUE;*/
-
-static VOID CALLBACK arrange_process_switching (LPVOID arg, DWORD timeLow, DWORD timeHigh) 
-{
-	swproc_moo ();
-}
-
-static void setup_tick (void)
-{
-	LARGE_INTEGER li;
-	g_tick_timer = CreateWaitableTimer(MOO_NULL, TRUE, MOO_NULL);
-	if (g_tick_timer)
-	{
-		li.QuadPart = -MOO_SECNSEC_TO_NSEC(0, 20000); /* 20000 microseconds. 0.02 seconds */
-		SetWaitableTimer (g_tick_timer, &li, 0, arrange_process_switching, MOO_NULL, FALSE);
-	}
-}
-
-static void cancel_tick (void)
-{
-	if (g_tick_timer)
-	{
-		CancelWaitableTimer (g_tick_timer);
-		CloseHandle (g_tick_timer);
-		g_tick_timer = MOO_NULL;
-	}
-}
-
-#elif defined(__OS2__)
-static TID g_tick_tid;
-static HEV g_tick_sem; 
-static HTIMER g_tick_timer;
-static int g_tick_done = 0;
-
-static void EXPENTRY os2_wait_for_timer_event (ULONG x)
-{
-	APIRET rc;
-	ULONG count;
-
-	rc = DosCreateEventSem (NULL, &g_tick_sem, DC_SEM_SHARED, FALSE);
-	if (rc != NO_ERROR)
-	{
-		/* xxxx */
-	}
-
-	rc = DosStartTimer (1L, (HSEM)g_tick_sem, &g_tick_timer);
-	if (rc != NO_ERROR)
-	{
-	}
-
-	while (!g_tick_done)
-	{
-		rc = DosWaitEventSem((HSEM)g_tick_sem, 5000L);
-		DosResetEventSem((HSEM)g_tick_sem, &count);
-		swproc_moo ();
-	}
-
-	DosStopTimer (g_tick_timer);
-	DosCloseEventSem ((HSEM)g_tick_sem);
-
-	g_tick_timer = NULL;
-	g_tick_sem = NULL;
-	DosExit (EXIT_THREAD, 0);
-}
-
-static void setup_tick (void)
-{
-	/* TODO: Error check */
-	DosCreateThread (&g_tick_tid, os2_wait_for_timer_event, 0, 0, 4096);
-}
-
-static void cancel_tick (void)
-{
-	if (g_tick_sem) DosPostEventSem (g_tick_sem);
-	g_tick_done = 1;
-}
-
-#elif defined(macintosh)
-
-static TMTask g_tmtask;
-static ProcessSerialNumber g_psn;
-
-#define TMTASK_DELAY 50 /* milliseconds if positive, microseconds(after negation) if negative */
-
-static pascal void timer_intr_handler (TMTask* task)
-{
-	swproc_moo ();
-	WakeUpProcess (&g_psn);
-	PrimeTime ((QElem*)&g_tmtask, TMTASK_DELAY);
-}
-
-static void setup_tick (void)
-{
-	GetCurrentProcess (&g_psn);
-	memset (&g_tmtask, 0, MOO_SIZEOF(g_tmtask));
-	g_tmtask.tmAddr = NewTimerProc (timer_intr_handler);
-	InsXTime ((QElem*)&g_tmtask);
-	PrimeTime ((QElem*)&g_tmtask, TMTASK_DELAY);
-}
-
-static void cancel_tick (void)
-{
-	RmvTime ((QElem*)&g_tmtask);
-	/*DisposeTimerProc (g_tmtask.tmAddr);*/
-}
-
-#elif defined(HAVE_SETITIMER) && defined(SIGVTALRM) && defined(ITIMER_VIRTUAL)
-
-static void arrange_process_switching (int sig)
-{
-	swproc_moo ();
-}
-
-static void setup_tick (void)
-{
-	struct itimerval itv;
-	struct sigaction act, oldact;
-
-	memset (&act, 0, sizeof(act));
-	sigemptyset (&act.sa_mask);
-	act.sa_handler = arrange_process_switching;
-	act.sa_flags = SA_RESTART;
-	sigaction (SIGVTALRM, &act, MOO_NULL);
-
-/*#define MOO_ITIMER_TICK 10000*/ /* microseconds. 0.01 seconds */
-#define MOO_ITIMER_TICK 20000 /* microseconds. 0.02 seconds. */
-	itv.it_interval.tv_sec = 0;
-	itv.it_interval.tv_usec = MOO_ITIMER_TICK;
-	itv.it_value.tv_sec = 0;
-	itv.it_value.tv_usec = MOO_ITIMER_TICK;
-	setitimer (ITIMER_VIRTUAL, &itv, MOO_NULL);
-}
-
-static void cancel_tick (void)
-{
-	struct itimerval itv;
-	struct sigaction act;
-
-	itv.it_interval.tv_sec = 0;
-	itv.it_interval.tv_usec = 0;
-	itv.it_value.tv_sec = 0; /* make setitimer() one-shot only */
-	itv.it_value.tv_usec = 0;
-	setitimer (ITIMER_VIRTUAL, &itv, MOO_NULL);
-
-	sigemptyset (&act.sa_mask); 
-	act.sa_handler = SIG_IGN; /* ignore the signal potentially fired by the one-shot arrange above */
-	act.sa_flags = 0;
-	sigaction (SIGVTALRM, &act, MOO_NULL);
-}
-#else
-#	error UNSUPPORTED
-#endif
-
-
 #if defined(_WIN32)
 static BOOL WINAPI handle_term (DWORD ctrl_type)
 {
@@ -627,9 +427,11 @@ int main (int argc, char* argv[])
 	MOO_DEBUG0 (moo, "COMPILE OK. STARTING EXECUTION...\n");
 	xret = 0;
 	g_moo = moo;
-	setup_tick ();
+	moo_start_ticker ();
 	setup_sigterm ();
 
+	moo_rcvtickstd (moo, 1);
+
 	objname.ptr = str_my_object;
 	objname.len = 8;
 	mthname.ptr = str_main;
@@ -640,7 +442,7 @@ int main (int argc, char* argv[])
 		xret = -1;
 	}
 
-	cancel_tick ();
+	moo_stop_ticker ();
 	clear_sigterm ();
 	g_moo = MOO_NULL;
 
diff --git a/moo/lib/moo-cfg.h.in b/moo/lib/moo-cfg.h.in
index 8141ec4..801cfd3 100644
--- a/moo/lib/moo-cfg.h.in
+++ b/moo/lib/moo-cfg.h.in
@@ -174,6 +174,12 @@
 /* Define to 1 if you have the `settimeofday' function. */
 #undef HAVE_SETTIMEOFDAY
 
+/* Define to 1 if you have the `sigaction' function. */
+#undef HAVE_SIGACTION
+
+/* Define to 1 if you have the `signal' function. */
+#undef HAVE_SIGNAL
+
 /* Define to 1 if you have the <signal.h> header file. */
 #undef HAVE_SIGNAL_H
 
@@ -348,6 +354,9 @@
 /* MB_LEN_MAX */
 #undef MOO_MBLEN_MAX
 
+/* NSIG */
+#undef MOO_NSIG
+
 /* offsetof(struct sockaddr, sa_family) */
 #undef MOO_OFFSETOF_SA_FAMILY
 
diff --git a/moo/lib/moo-std.h b/moo/lib/moo-std.h
index 8322082..48f157c 100644
--- a/moo/lib/moo-std.h
+++ b/moo/lib/moo-std.h
@@ -78,6 +78,14 @@ typedef struct moo_iostd_t moo_iostd_t;
 extern "C" {
 #endif
 
+MOO_EXPORT void moo_start_ticker (
+	void
+);
+
+MOO_EXPORT void moo_stop_ticker (
+	void
+);
+
 MOO_EXPORT moo_t* moo_openstd (
 	moo_oow_t           xtnsize, 
 	const moo_cfgstd_t* cfg,
@@ -97,6 +105,12 @@ MOO_EXPORT int moo_compilestd(
 	const moo_iostd_t* in,
 	moo_oow_t          count
 );
+
+MOO_EXPORT void moo_rcvtickstd (
+	moo_t*             moo,
+	int                v
+);
+
 #if defined(__cplusplus)
 }
 #endif
diff --git a/moo/lib/std.c b/moo/lib/std.c
index 021c0d2..fadc844 100644
--- a/moo/lib/std.c
+++ b/moo/lib/std.c
@@ -265,6 +265,7 @@ struct xtn_t
 	moo_t* prev;
 
 	int vm_running;
+	int rcv_tick;
 
 	struct
 	{
@@ -359,7 +360,6 @@ struct xtn_t
 #define GET_XTN(moo) ((xtn_t*)moo_getxtn(moo))
 
 static moo_t* g_moo = MOO_NULL;
-static int g_moo_tick_active = 0;
 
 /* ========================================================================= */
 
@@ -2604,6 +2604,8 @@ static void vm_sleep (moo_t* moo, const moo_ntime_t* dur)
 
 /* ========================================================================= */
 
+#if defined(HAVE_SIGACTION)
+
 typedef struct sig_state_t sig_state_t;
 struct sig_state_t
 {
@@ -2615,14 +2617,16 @@ struct sig_state_t
 
 typedef void (*sig_handler_t) (int sig);
 
-#if !defined(NSIGS)
-#	define NSIGS 100 /* TODO: change this */
-#endif
-static sig_state_t g_sig_state[NSIGS];
+static sig_state_t g_sig_state[MOO_NSIG];
 
 static void dispatch_siginfo (int sig, siginfo_t* si, void* ctx)
 {
-	((sig_handler_t)g_sig_state[sig].handler) (sig);
+	if (g_sig_state[sig].handler != (moo_oow_t)SIG_IGN &&
+	    g_sig_state[sig].handler != (moo_oow_t)SIG_DFL)
+	{
+		((sig_handler_t)g_sig_state[sig].handler) (sig);
+	}
+
 	if (g_sig_state[sig].old_handler && 
 	    g_sig_state[sig].old_handler != (moo_oow_t)SIG_IGN &&
 	    g_sig_state[sig].old_handler != (moo_oow_t)SIG_DFL)
@@ -2633,7 +2637,12 @@ static void dispatch_siginfo (int sig, siginfo_t* si, void* ctx)
 
 static void dispatch_signal (int sig)
 {
-	((sig_handler_t)g_sig_state[sig].handler) (sig);
+	if (g_sig_state[sig].handler != (moo_oow_t)SIG_IGN &&
+	    g_sig_state[sig].handler != (moo_oow_t)SIG_DFL)
+	{
+		((sig_handler_t)g_sig_state[sig].handler) (sig);
+	}
+
 	if (g_sig_state[sig].old_handler && 
 	    g_sig_state[sig].old_handler != (moo_oow_t)SIG_IGN &&
 	    g_sig_state[sig].old_handler != (moo_oow_t)SIG_DFL)
@@ -2647,6 +2656,7 @@ static int set_signal_handler (int sig, sig_handler_t handler, int extra_flags)
 	if (g_sig_state[sig].handler)
 	{
 		/* already set - allow handler change. ignore extra_flags. */
+		if (g_sig_state[sig].handler == (moo_oow_t)handler) return -1;
 		g_sig_state[sig].handler = (moo_oow_t)handler;
 	}
 	else
@@ -2713,9 +2723,10 @@ static int unset_signal_handler (int sig)
 	return 0;
 }
 
+#endif
 /* ========================================================================= */
 
-static MOO_INLINE void swproc_all (void)
+static MOO_INLINE void swproc_all_moos (void)
 {
 	/* TODO: make this atomic */
 	if (g_moo)
@@ -2723,15 +2734,15 @@ static MOO_INLINE void swproc_all (void)
 		moo_t* moo = g_moo;
 		do
 		{
-			moo_switchprocess (moo);
-			moo = GET_XTN(moo)->next;
+			xtn_t* xtn = GET_XTN(moo);
+			if (xtn->rcv_tick) moo_switchprocess (moo);
+			moo = xtn->next;
 		}
 		while (moo);
 	}
 	/* TODO: make this atomic */
 }
 
-
 #if defined(__DOS__) && (defined(_INTELC32_) || defined(__WATCOMC__))
 
 #if defined(_INTELC32_)
@@ -2755,48 +2766,61 @@ static void __interrupt dos_timer_intr_handler (void)
 	*/
 
 	/* The timer interrupt (normally) occurs 18.2 times per second. */
-	swproc_moo ();
+	swproc_all_moos ();
 	_chain_intr (dos_prev_timer_intr_handler);
 }
 
-static void setup_tick (void)
+static void moo_start_ticker (void)
 {
-	dos_prev_timer_intr_handler = _dos_getvect(0x1C);
-	_dos_setvect (0x1C, dos_timer_intr_handler);
+	if (++ticker_started == 1)
+	{
+		dos_prev_timer_intr_handler = _dos_getvect(0x1C);
+		_dos_setvect (0x1C, dos_timer_intr_handler);
+	}
 }
 
-static void cancel_tick (void)
+static void moo_stop_ticker (void)
 {
-	_dos_setvect (0x1C, dos_prev_timer_intr_handler);
+	if (ticker_started > 0 && --ticker_started == 0)
+	{
+		_dos_setvect (0x1C, dos_prev_timer_intr_handler);
+	}
 }
 
 #elif defined(_WIN32)
 
 static HANDLE win_tick_timer = MOO_NULL; /*INVALID_HANDLE_VALUE;*/
+static moo_uint32_t ticker_started = 0;
 
 static VOID CALLBACK arrange_process_switching (LPVOID arg, DWORD timeLow, DWORD timeHigh) 
 {
-	swproc_moo ();
+	swproc_all_moos ();
 }
 
-static void setup_tick (void)
+static void moo_start_ticker (void)
 {
-	LARGE_INTEGER li;
-	win_tick_timer = CreateWaitableTimer(MOO_NULL, TRUE, MOO_NULL);
-	if (win_tick_timer)
+	if (++ticker_started == 1)
 	{
-		li.QuadPart = -MOO_SECNSEC_TO_NSEC(0, 20000); /* 20000 microseconds. 0.02 seconds */
-		SetWaitableTimer (win_tick_timer, &li, 0, arrange_process_switching, MOO_NULL, FALSE);
+		LARGE_INTEGER li;
+		win_tick_timer = CreateWaitableTimer(MOO_NULL, TRUE, MOO_NULL);
+		if (win_tick_timer)
+		{
+			li.QuadPart = -MOO_SECNSEC_TO_NSEC(0, 20000); /* 20000 microseconds. 0.02 seconds */
+			SetWaitableTimer (win_tick_timer, &li, 0, arrange_process_switching, MOO_NULL, FALSE);
+		}
 	}
 }
 
-static void cancel_tick (void)
+static void moo_stop_ticker (void)
 {
-	if (win_tick_timer)
+	if (ticker_started > 0 && --ticker_started == 0)
 	{
-		CancelWaitableTimer (win_tick_timer);
-		CloseHandle (win_tick_timer);
-		win_tick_timer = MOO_NULL;
+		if (win_tick_timer)
+		{
+			CancelWaitableTimer (win_tick_timer);
+			CloseHandle (win_tick_timer);
+			win_tick_timer = MOO_NULL;
+		}
 	}
 }
 
@@ -2805,6 +2829,7 @@ static TID os2_tick_tid;
 static HEV os2_tick_sem; 
 static HTIMER os2_tick_timer;
 static int os2_tick_done = 0;
+static moo_uint32_t ticker_started = 0;
 
 static void EXPENTRY os2_wait_for_timer_event (ULONG x)
 {
@@ -2826,7 +2851,7 @@ static void EXPENTRY os2_wait_for_timer_event (ULONG x)
 	{
 		rc = DosWaitEventSem((HSEM)os2_tick_sem, 5000L);
 		DosResetEventSem((HSEM)os2_tick_sem, &count);
-		swproc_moo ();
+		swproc_all_moos ();
 	}
 
 	DosStopTimer (os2_tick_timer);
@@ -2837,16 +2862,22 @@ static void EXPENTRY os2_wait_for_timer_event (ULONG x)
 	DosExit (EXIT_THREAD, 0);
 }
 
-static void setup_tick (void)
+static void moo_start_ticker (void)
 {
-	/* TODO: Error check */
-	DosCreateThread (&os2_tick_tid, os2_wait_for_timer_event, 0, 0, 4096);
+	if (++ticker_started == 1)
+	{
+		/* TODO: Error check */
+		DosCreateThread (&os2_tick_tid, os2_wait_for_timer_event, 0, 0, 4096);
+	}
 }
 
-static void cancel_tick (void)
+static void moo_stop_ticker (void)
 {
-	if (os2_tick_sem) DosPostEventSem (os2_tick_sem);
-	os2_tick_done = 1;
+	if (ticker_started > 0 && --ticker_started == 0)
+	{
+		if (os2_tick_sem) DosPostEventSem (os2_tick_sem);
+		os2_tick_done = 1;
+	}
 }
 
 #elif defined(macintosh)
@@ -2858,12 +2889,12 @@ static ProcessSerialNumber mac_psn;
 
 static pascal void timer_intr_handler (TMTask* task)
 {
-	swproc_moo ();
+	swproc_all_moos ();
 	WakeUpProcess (&mac_psn);
 	PrimeTime ((QElem*)&mac_tmtask, TMTASK_DELAY);
 }
 
-static void setup_tick (void)
+static void moo_start_ticker (void)
 {
 	GetCurrentProcess (&mac_psn);
 	memset (&mac_tmtask, 0, MOO_SIZEOF(mac_tmtask));
@@ -2872,7 +2903,7 @@ static void setup_tick (void)
 	PrimeTime ((QElem*)&mac_tmtask, TMTASK_DELAY);
 }
 
-static void cancel_tick (void)
+static void moo_stop_ticker (void)
 {
 	RmvTime ((QElem*)&mac_tmtask);
 	/*DisposeTimerProc (mac_tmtask.tmAddr);*/
@@ -2882,58 +2913,47 @@ static void cancel_tick (void)
 
 static void arrange_process_switching (int sig)
 {
-	swproc_moo ();
+	swproc_all_moos ();
 }
 
-static void setup_tick (void)
+static moo_uint32_t ticker_started = 0;
+
+void moo_start_ticker (void)
 {
-	struct itimerval itv;
-
-#if 0
-	struct sigaction act;
-
-	memset (&act, 0, sizeof(act));
-	sigemptyset (&act.sa_mask);
-	act.sa_handler = arrange_process_switching;
-	act.sa_flags = SA_RESTART;
-	sigaction (SIGVTALRM, &act, MOO_NULL);
-#else
-	set_signal_handler (SIGVTALRM, arrange_process_switching, SA_RESTART);
-#endif
-
-/*#define MOO_ITIMER_TICK 10000*/ /* microseconds. 0.01 seconds */
-#define MOO_ITIMER_TICK 20000 /* microseconds. 0.02 seconds. */
-	itv.it_interval.tv_sec = 0;
-	itv.it_interval.tv_usec = MOO_ITIMER_TICK;
-	itv.it_value.tv_sec = 0;
-	itv.it_value.tv_usec = MOO_ITIMER_TICK;
-	setitimer (ITIMER_VIRTUAL, &itv, MOO_NULL);
+	if (++ticker_started == 1)
+	{
+		if (set_signal_handler(SIGVTALRM, arrange_process_switching, SA_RESTART) >= 0)
+		{
+			struct itimerval itv;
+		/*#define MOO_ITIMER_TICK 10000*/ /* microseconds. 0.01 seconds */
+		#define MOO_ITIMER_TICK 20000 /* microseconds. 0.02 seconds. */
+			itv.it_interval.tv_sec = 0;
+			itv.it_interval.tv_usec = MOO_ITIMER_TICK;
+			itv.it_value.tv_sec = 0;
+			itv.it_value.tv_usec = MOO_ITIMER_TICK;
+			setitimer (ITIMER_VIRTUAL, &itv, MOO_NULL);
+		}
+	}
 }
 
-static void cancel_tick (void)
+void moo_stop_ticker (void)
 {
-	struct itimerval itv;
-#if 0
-	struct sigaction act;
-#endif
-
-	itv.it_interval.tv_sec = 0;
-	itv.it_interval.tv_usec = 0;
-	itv.it_value.tv_sec = 0; /* make setitimer() one-shot only */
-	itv.it_value.tv_usec = 0;
-	setitimer (ITIMER_VIRTUAL, &itv, MOO_NULL);
-
-#if 0
-	sigemptyset (&act.sa_mask); 
-	act.sa_handler = SIG_IGN; /* ignore the signal potentially fired by the one-shot arrange above */
-	act.sa_flags = 0;
-	sigaction (SIGVTALRM, &act, MOO_NULL);
-#else
-	/* ignore the signal potentially fired by the one-shot arrange above
-	 * instead of unsetting the signal handler */
-	set_signal_handler (SIGVTALRM, SIG_IGN, 0);
-#endif
+	if (ticker_started > 0 && --ticker_started == 0)
+	{
+		/* ignore the signal fired by the activated timer.
+		 * unsetting the signal may cause the program to terminate(default action) */
+		if (set_signal_handler(SIGVTALRM, SIG_IGN, 0) >= 0)
+		{
+			struct itimerval itv;
+			itv.it_interval.tv_sec = 0;
+			itv.it_interval.tv_usec = 0;
+			itv.it_value.tv_sec = 0; /* make setitimer() one-shot only */
+			itv.it_value.tv_usec = 0;
+			setitimer (ITIMER_VIRTUAL, &itv, MOO_NULL);
+		}
+	}
 }
+
 #else
 #	error UNSUPPORTED
 #endif
@@ -3275,9 +3295,11 @@ static MOO_INLINE void chain (moo_t* moo)
 	xtn_t* xtn = GET_XTN(moo);
 
 	/* TODO: make this atomic */
+	xtn->prev = MOO_NULL;
+	xtn->next = g_moo;
+
 	if (g_moo) GET_XTN(g_moo)->prev = moo;
 	else g_moo = moo;
-	xtn->next = g_moo;
 	/* TODO: make this atomic */
 }
 
@@ -3369,12 +3391,11 @@ void moo_abortstd (moo_t* moo)
 	moo_abort (moo);
 }
 
-int moo_compilestd(moo_t* moo, const moo_iostd_t* in, moo_oow_t count)
+int moo_compilestd (moo_t* moo, const moo_iostd_t* in, moo_oow_t count)
 {
-	xtn_t* xtn;
+	xtn_t* xtn = GET_XTN(moo);
 	moo_oow_t i;
 
-	xtn = GET_XTN(moo);
 	for (i = 0; i < count; i++)
 	{
 		xtn->in = &in[i];
@@ -3383,3 +3404,9 @@ int moo_compilestd(moo_t* moo, const moo_iostd_t* in, moo_oow_t count)
 
 	return 0;
 };
+
+void moo_rcvtickstd (moo_t* moo, int v)
+{
+	xtn_t* xtn = GET_XTN(moo);
+	xtn->rcv_tick = v;
+}
diff --git a/moo/mod/Makefile.in b/moo/mod/Makefile.in
index 721f361..ded4eec 100644
--- a/moo/mod/Makefile.in
+++ b/moo/mod/Makefile.in
@@ -419,6 +419,7 @@ pdfdir = @pdfdir@
 prefix = @prefix@
 program_transform_name = @program_transform_name@
 psdir = @psdir@
+runstatedir = @runstatedir@
 sbindir = @sbindir@
 sharedstatedir = @sharedstatedir@
 srcdir = @srcdir@