--- a/src/animate.c	Sun Aug 10 18:27:52 2008 +0800
+++ b/src/animate.c	Sun Aug 10 20:25:14 2008 +0800
@@ -450,6 +450,67 @@
     return (mb_action_t *)chg;
 }
 
+
+typedef struct _mb_visibility mb_visibility_t;
+
+struct _mb_visibility {
+    mb_action_t action;
+    int visibility;
+    coord_t *coord;
+};
+
+static void mb_visibility_start(mb_action_t *act,
+				const mb_timeval_t *now,
+				const mb_timeval_t *playing_time,
+				redraw_man_t *rdman) {
+    mb_visibility_t *visibility = (mb_visibility_t *)act;
+
+    switch(visibility->visibility) {
+    case VIS_VISIBLE:
+	coord_show(visibility->coord);
+	break;
+    case VIS_HIDDEN:
+	coord_hide(visibility->coord);
+	break;
+    }
+    rdman_coord_changed(rdman, visibility->coord);
+}
+
+static void mb_visibility_step(mb_action_t *act,
+			       const mb_timeval_t *now,
+			       redraw_man_t *rdman) {
+}
+
+static void mb_visibility_stop(mb_action_t *act,
+			       const mb_timeval_t *now,
+			       redraw_man_t *rdman) {
+}
+
+static void mb_visibility_free(mb_action_t *act) {
+    free(act);
+}
+
+mb_action_t *mb_visibility_new(int visib, coord_t *coord,
+			       mb_word_t *word) {
+    mb_visibility_t *visibility;
+
+    visibility = (mb_visibility_t *)malloc(sizeof(mb_visibility_t));
+    if(visibility == NULL)
+	return NULL;
+
+    visibility->visibility = visib;
+    visibility->coord = coord;
+
+    visibility->action.start = mb_visibility_start;
+    visibility->action.step = mb_visibility_step;
+    visibility->action.stop = mb_visibility_stop;
+    visibility->action.free = mb_visibility_free;
+
+    mb_word_add_action(word, (mb_action_t *)visibility);
+
+    return (mb_action_t *)visibility;
+}
+
 #ifdef UNITTEST
 
 #include <CUnit/Basic.h>