Index: src/npw-viewer.c
===================================================================
--- src/npw-viewer.c	(révision 645)
+++ src/npw-viewer.c	(copie de travail)
@@ -163,6 +163,23 @@
     CorePart    core;
 } WidgetRec, CoreRec;
 
+typedef struct _TimerEventRec {
+    struct timeval        te_timer_value;
+    struct _TimerEventRec *te_next;
+    XtTimerCallbackProc   te_proc;
+    XtAppContext          app;
+    XtPointer             te_closure;
+} TimerEventRec;
+
+struct _XtAppStruct {
+    XtAppContext next;          /* link to next app in process context */
+    void *process;              /* back pointer to our process context */
+    void *destroy_callbacks;
+    Display **list;
+    TimerEventRec *timerQueue;
+    /* ... don't care about other members */
+};
+
 extern void XtResizeWidget(
     Widget              /* widget */,
     _XtDimension        /* width */,
@@ -3151,18 +3168,84 @@
 
 // Xt events
 static GPollFD xt_event_poll_fd;
+static const int XT_MAX_TIMEOUT = 25;
+static const int XT_MAX_EVENTS  = 5;
 
+static void xt_has_compatible_appcontext_cb(XtPointer closure, XtIntervalId *id)
+{
+  /* dummy function, never called */
+}
+
+static int xt_has_compatible_appcontext(void)
+{
+  int is_compatible;
+  XtIntervalId id;
+  TimerEventRec *tq, *tq_probe;
+
+  /* XXX: poor man's attempt to guess the pointer to the next
+	 allocated TimerEventRec. Besides, we MUST be the first to call
+	 XtAppAddTimeOut() so that to be sure any "free" TimerEventRec
+	 pointer cache is empty. */
+  tq = XtNew(TimerEventRec);
+  XtFree((char *)tq);
+  tq_probe = XtNew(TimerEventRec);
+  XtFree((char *)tq_probe);
+  if (tq != tq_probe)
+	return 0;
+
+  id = XtAppAddTimeOut(x_app_context, 0,
+					   xt_has_compatible_appcontext_cb,
+					   GUINT_TO_POINTER(0xdeadbeef));
+
+  tq = x_app_context->timerQueue;
+  is_compatible = tq == tq_probe
+	&& tq->app == x_app_context
+	&& tq->te_proc == xt_has_compatible_appcontext_cb
+	&& tq->te_closure == GUINT_TO_POINTER(0xdeadbeef)
+	;
+
+  XtRemoveTimeOut(id);
+  return is_compatible;
+}
+
+static int xt_get_next_timeout(GSource *source)
+{
+  static int has_compatible_appcontext = -1;
+  if (has_compatible_appcontext < 0) {
+	if ((has_compatible_appcontext = xt_has_compatible_appcontext()) == 0)
+	  npw_printf("WARNING: xt_get_next_timeout() is not optimizable\n");
+  }
+  if (has_compatible_appcontext) {
+	/* We can block if there is no timer registered */
+	if (x_app_context->timerQueue == NULL)
+	  return -1;
+	/* Determine delay to next timeout. Zero means timeout expired */
+	struct timeval *next = &x_app_context->timerQueue->te_timer_value;
+	GTimeVal now;
+	int64_t diff;
+	g_source_get_current_time(source, &now);
+	if ((diff = (int64_t)next->tv_sec - (int64_t)now.tv_sec) < 0)
+	  return 0;
+	if ((diff = diff*1000 + ((int64_t)next->tv_usec - (int64_t)now.tv_usec)/1000) <= 0)
+	  return 0;
+	return diff;
+  }
+  return XT_MAX_TIMEOUT;
+}
+
 static gboolean xt_event_prepare(GSource *source, gint *timeout)
 {
   int mask = XtAppPending(x_app_context);
-  return mask & XtIMXEvent;
+  if (mask)
+	return TRUE;
+  return (*timeout = xt_get_next_timeout(source)) == 0;
 }
 
 static gboolean xt_event_check(GSource *source)
 {
   if (xt_event_poll_fd.revents & G_IO_IN) {
 	int mask = XtAppPending(x_app_context);
-	if (mask & XtIMXEvent)
+	if (mask)
 	  return TRUE;
   }
   return FALSE;
@@ -3171,11 +3254,13 @@
 static gboolean xt_event_dispatch(GSource *source, GSourceFunc callback, gpointer user_data)
 {
   int i;
-  for (i = 0; i < 5; i++) {
+  /* Process only a few events here so that to give some time to other
+	 sources as well (e.g. RPC) */
+  for (i = 0; i < XT_MAX_EVENTS; i++) {
 	int mask = XtAppPending(x_app_context);
-	if ((mask & XtIMXEvent) == 0)
+	if (mask == 0)
 	  break;
-	XtAppProcessEvent(x_app_context, XtIMXEvent);
+	XtAppProcessEvent(x_app_context, XtIMAll);
   }
   return TRUE;
 }
@@ -3189,17 +3274,6 @@
   (GSourceDummyMarshal)NULL
 };
 
-static gboolean xt_event_polling_timer_callback(gpointer user_data)
-{
-  int i;
-  for (i = 0; i < 5; i++) {
-	if ((XtAppPending(x_app_context) & (XtIMAll & ~XtIMXEvent)) == 0)
-	  break;
-	XtAppProcessEvent(x_app_context, XtIMAll & ~XtIMXEvent);
-  }
-  return TRUE;
-}
-
 // RPC events
 static GPollFD rpc_event_poll_fd;
 
@@ -3316,10 +3393,6 @@
   xt_event_poll_fd.revents = 0;
   g_source_add_poll(xt_source, &xt_event_poll_fd);
 
-  gint xt_polling_timer_id = g_timeout_add(25,
-										   xt_event_polling_timer_callback,
-										   NULL);
-
   // Initialize RPC events listener
   GSource *rpc_source = g_source_new(&rpc_event_funcs, sizeof(GSource));
   if (rpc_source == NULL) {
@@ -3337,7 +3410,6 @@
   gtk_main();
   D(bug("--- EXIT ---\n"));
 
-  g_source_remove(xt_polling_timer_id);
   g_source_destroy(rpc_source);
   g_source_destroy(xt_source);