diff --git a/src/base/pages.c b/src/base/pages.c
index d9999e325..15843a865 100644
--- a/src/base/pages.c
+++ b/src/base/pages.c
@@ -38,22 +38,13 @@ ret_t pages_set_active(widget_t* widget, uint32_t index) {
 }
 
 ret_t pages_set_active_by_name(widget_t* widget, const char* name) {
-  uint32_t i = 0;
-  uint32_t nr = 0;
-  widget_t** children = NULL;
   return_value_if_fail(widget != NULL && name != NULL, RET_BAD_PARAMS);
 
-  if (widget->children && widget->children->elms) {
-    nr = widget->children->size;
-    children = (widget_t**)(widget->children->elms);
-
-    for (i = 0; i < nr; i++) {
-      widget_t* iter = children[i];
-      if (iter->name.str && tk_str_eq(iter->name.str, name)) {
-        return pages_set_active(widget, i);
-      }
-    }
+  WIDGET_FOR_EACH_CHILD_BEGIN(widget, iter, i)
+  if (tk_str_eq(iter->name.str, name)) {
+    return pages_set_active(widget, i);
   }
+  WIDGET_FOR_EACH_CHILD_END();
 
   return RET_NOT_FOUND;
 }
diff --git a/src/base/scroll_view.c b/src/base/scroll_view.c
index e603a4bc6..44acca152 100755
--- a/src/base/scroll_view.c
+++ b/src/base/scroll_view.c
@@ -65,24 +65,16 @@ static ret_t scroll_view_update_virtual_size(widget_t* widget) {
   int32_t virtual_w = tk_max(scroll_view->virtual_w, widget->w);
   int32_t virtual_h = tk_max(scroll_view->virtual_h, widget->h);
 
-  if (widget->children != NULL) {
-    int32_t i = 0;
-    int32_t n = 0;
-
-    for (i = 0, n = widget->children->size; i < n; i++) {
-      widget_t* iter = (widget_t*)(widget->children->elms[i]);
-      int32_t r = iter->x + iter->w;
-      int32_t b = iter->y + iter->h;
-
-      if (r > virtual_w) {
-        virtual_w = r;
-      }
-
-      if (b > virtual_h) {
-        virtual_h = b;
-      }
-    }
+  WIDGET_FOR_EACH_CHILD_BEGIN(widget, iter, i)
+  int32_t r = iter->x + iter->w;
+  int32_t b = iter->y + iter->h;
+  if (r > virtual_w) {
+    virtual_w = r;
   }
+  if (b > virtual_h) {
+    virtual_h = b;
+  }
+  WIDGET_FOR_EACH_CHILD_END();
 
   scroll_view->virtual_w = virtual_w;
   scroll_view->virtual_h = virtual_h;
diff --git a/src/base/utils.h b/src/base/utils.h
index 5d1fd840f..58f70a92a 100644
--- a/src/base/utils.h
+++ b/src/base/utils.h
@@ -43,7 +43,8 @@ void* tk_pixel_copy(void* dst, const void* src, uint32_t size, uint8_t bpp);
 int tk_snprintf(char* str, size_t size, const char* format, ...);
 ret_t filename_to_name(const char* filename, char* str, uint32_t size);
 
-#define tk_str_eq(s1, s2) (*(s1) == *(s2) && strcmp((s1), (s2)) == 0)
+#define tk_str_eq(s1, s2) \
+  ((s1) != NULL) && ((s2) != NULL) && (*(s1) == *(s2) && strcmp((s1), (s2)) == 0)
 #define tk_fequal(f1, f2) (fabs((f1) - (f2)) < 0.0000001)
 
 END_C_DECLS
diff --git a/src/base/widget.c b/src/base/widget.c
index e21e38f4f..40bef2824 100644
--- a/src/base/widget.c
+++ b/src/base/widget.c
@@ -136,14 +136,9 @@ ret_t widget_re_translate_text(widget_t* widget) {
     widget_invalidate(widget, NULL);
   }
 
-  if (widget->children != NULL) {
-    int32_t i = 0;
-    int32_t n = 0;
-    for (i = 0, n = widget->children->size; i < n; i++) {
-      widget_t* iter = (widget_t*)(widget->children->elms[i]);
-      widget_re_translate_text(iter);
-    }
-  }
+  WIDGET_FOR_EACH_CHILD_BEGIN(widget, iter, i)
+  widget_re_translate_text(iter);
+  WIDGET_FOR_EACH_CHILD_END();
 
   return RET_OK;
 #else
@@ -258,17 +253,12 @@ ret_t widget_set_anchor(widget_t* widget, float_t anchor_x, float_t anchor_y) {
 }
 
 ret_t widget_destroy_children(widget_t* widget) {
-  int32_t i = 0;
-  int32_t n = 0;
   return_value_if_fail(widget != NULL, RET_BAD_PARAMS);
 
-  if (widget->children != NULL) {
-    for (i = 0, n = widget->children->size; i < n; i++) {
-      widget_t* iter = (widget_t*)(widget->children->elms[i]);
-      widget_destroy_only(iter);
-    }
-    widget->children->size = 0;
-  }
+  WIDGET_FOR_EACH_CHILD_BEGIN(widget, iter, i)
+  widget_destroy_only(iter);
+  WIDGET_FOR_EACH_CHILD_END();
+  widget->children->size = 0;
 
   return RET_OK;
 }
@@ -301,55 +291,41 @@ ret_t widget_remove_child(widget_t* widget, widget_t* child) {
     widget->key_target = NULL;
   }
 
-  child->parent = NULL;
   if (widget->vt->on_remove_child) {
     if (widget->vt->on_remove_child(widget, child) == RET_OK) {
       return RET_OK;
     }
   }
 
+  child->parent = NULL;
   return array_remove(widget->children, NULL, child, NULL);
 }
 
 static widget_t* widget_lookup_child(widget_t* widget, const char* name) {
-  int32_t i = 0;
-  int32_t n = 0;
   return_value_if_fail(widget != NULL && name != NULL, NULL);
 
-  if (widget->children != NULL) {
-    for (i = 0, n = widget->children->size; i < n; i++) {
-      widget_t* iter = (widget_t*)(widget->children->elms[i]);
-      if (iter->name.str == NULL) {
-        continue;
-      }
-
-      if (str_eq(&(iter->name), name)) {
-        return iter;
-      }
-    }
+  WIDGET_FOR_EACH_CHILD_BEGIN(widget, iter, i)
+  if (iter->name.str != NULL && str_eq(&(iter->name), name)) {
+    return iter;
   }
+  WIDGET_FOR_EACH_CHILD_END()
 
   return NULL;
 }
 
 static widget_t* widget_lookup_all(widget_t* widget, const char* name) {
-  int32_t i = 0;
-  int32_t n = 0;
   return_value_if_fail(widget != NULL && name != NULL, NULL);
 
-  if (widget->children != NULL) {
-    for (i = 0, n = widget->children->size; i < n; i++) {
-      widget_t* iter = (widget_t*)(widget->children->elms[i]);
-      if (str_eq(&(iter->name), name)) {
-        return iter;
-      } else {
-        iter = widget_lookup_all(iter, name);
-        if (iter != NULL) {
-          return iter;
-        }
-      }
+  WIDGET_FOR_EACH_CHILD_BEGIN(widget, iter, i)
+  if (iter->name.str != NULL && str_eq(&(iter->name), name)) {
+    return iter;
+  } else {
+    iter = widget_lookup_all(iter, name);
+    if (iter != NULL) {
+      return iter;
     }
   }
+  WIDGET_FOR_EACH_CHILD_END();
 
   return NULL;
 }
@@ -375,17 +351,12 @@ static ret_t widget_set_visible_self(widget_t* widget, bool_t visible) {
 }
 
 static ret_t widget_set_visible_recursive(widget_t* widget, bool_t visible) {
-  int32_t i = 0;
-  int32_t n = 0;
   return_value_if_fail(widget != NULL, RET_BAD_PARAMS);
 
   widget->visible = visible;
-  if (widget->children != NULL) {
-    for (i = 0, n = widget->children->size; i < n; i++) {
-      widget_t* iter = (widget_t*)(widget->children->elms[i]);
-      widget_set_visible_recursive(iter, visible);
-    }
-  }
+  WIDGET_FOR_EACH_CHILD_BEGIN(widget, iter, i)
+  widget_set_visible_recursive(iter, visible);
+  WIDGET_FOR_EACH_CHILD_END()
 
   return RET_OK;
 }
@@ -1045,24 +1016,15 @@ ret_t widget_ungrab(widget_t* widget, widget_t* child) {
 }
 
 ret_t widget_foreach(widget_t* widget, tk_visit_t visit, void* ctx) {
-  int32_t i = 0;
-  int32_t nr = 0;
-  widget_t** children = NULL;
   return_value_if_fail(widget != NULL && visit != NULL, RET_BAD_PARAMS);
 
   if (visit(ctx, widget) != RET_OK) {
     return RET_DONE;
   }
 
-  if (widget->children && widget->children->elms) {
-    nr = widget->children->size;
-    children = (widget_t**)(widget->children->elms);
-
-    for (i = 0; i < nr; i++) {
-      widget_t* iter = children[i];
-      widget_foreach(iter, visit, ctx);
-    }
-  }
+  WIDGET_FOR_EACH_CHILD_BEGIN(widget, iter, i)
+  widget_foreach(iter, visit, ctx);
+  WIDGET_FOR_EACH_CHILD_END()
 
   return RET_OK;
 }
@@ -1125,17 +1087,12 @@ ret_t widget_destroy(widget_t* widget) {
 }
 
 static ret_t widget_set_dirty(widget_t* widget) {
-  int32_t i = 0;
-  int32_t n = 0;
   return_value_if_fail(widget != NULL, RET_BAD_PARAMS);
 
   widget->dirty = TRUE;
-  if (widget->children != NULL) {
-    for (i = 0, n = widget->children->size; i < n; i++) {
-      widget_t* iter = (widget_t*)(widget->children->elms[i]);
-      widget_set_dirty(iter);
-    }
-  }
+  WIDGET_FOR_EACH_CHILD_BEGIN(widget, iter, i)
+  widget_set_dirty(iter);
+  WIDGET_FOR_EACH_CHILD_END();
 
   return RET_OK;
 }
diff --git a/src/base/widget_vtable.c b/src/base/widget_vtable.c
index 7fbaf7440..acc99e7ab 100644
--- a/src/base/widget_vtable.c
+++ b/src/base/widget_vtable.c
@@ -59,33 +59,28 @@ ret_t widget_on_paint_self_default(widget_t* widget, canvas_t* c) {
 }
 
 ret_t widget_on_paint_children_default(widget_t* widget, canvas_t* c) {
-  uint32_t i = 0;
-  uint32_t nr = 0;
   return_value_if_fail(widget != NULL && c != NULL, RET_BAD_PARAMS);
 
-  if (widget->children != NULL) {
-    for (i = 0, nr = widget->children->size; i < nr; i++) {
-      widget_t* iter = (widget_t*)(widget->children->elms[i]);
-      int32_t left = c->ox + iter->x;
-      int32_t top = c->oy + iter->y;
-      int32_t bottom = top + iter->h;
-      int32_t right = left + iter->w;
+  WIDGET_FOR_EACH_CHILD_BEGIN(widget, iter, i)
+  int32_t left = c->ox + iter->x;
+  int32_t top = c->oy + iter->y;
+  int32_t bottom = top + iter->h;
+  int32_t right = left + iter->w;
 
-      if (!iter->visible) {
-        iter->dirty = FALSE;
-        continue;
-      }
-
-      if (left > c->clip_right || right < c->clip_left || top > c->clip_bottom ||
-          bottom < c->clip_top) {
-        iter->dirty = FALSE;
-        continue;
-      }
-
-      widget_paint(iter, c);
-    }
+  if (!iter->visible) {
+    iter->dirty = FALSE;
+    continue;
   }
 
+  if (left > c->clip_right || right < c->clip_left || top > c->clip_bottom ||
+      bottom < c->clip_top) {
+    iter->dirty = FALSE;
+    continue;
+  }
+
+  widget_paint(iter, c);
+  WIDGET_FOR_EACH_CHILD_END();
+
   return RET_OK;
 }
 
@@ -180,26 +175,20 @@ static ret_t point_to_local(widget_t* widget, point_t* p) {
   return RET_OK;
 }
 widget_t* widget_find_target_default(widget_t* widget, xy_t x, xy_t y) {
-  uint32_t i = 0;
-  uint32_t n = 0;
   point_t p = {x, y};
   return_value_if_fail(widget != NULL, NULL);
 
   point_to_local(widget, &p);
-  if (widget->children != NULL && widget->children->size > 0) {
-    xy_t xx = p.x;
-    xy_t yy = p.y;
-    n = widget->children->size;
-    for (i = n; i > 0; i--) {
-      widget_t* iter = (widget_t*)(widget->children->elms[i - 1]);
-      xy_t r = iter->x + iter->w;
-      xy_t b = iter->y + iter->h;
+  WIDGET_FOR_EACH_CHILD_BEGIN_R(widget, iter, i)
+  xy_t xx = p.x;
+  xy_t yy = p.y;
+  xy_t r = iter->x + iter->w;
+  xy_t b = iter->y + iter->h;
 
-      if (iter->enable && xx >= iter->x && yy >= iter->y && xx <= r && yy <= b) {
-        return iter;
-      }
-    }
+  if (iter->enable && xx >= iter->x && yy >= iter->y && xx <= r && yy <= b) {
+    return iter;
   }
+  WIDGET_FOR_EACH_CHILD_END();
 
   return NULL;
 }
diff --git a/src/base/window_manager.c b/src/base/window_manager.c
index a75826f4b..e6cb72667 100644
--- a/src/base/window_manager.c
+++ b/src/base/window_manager.c
@@ -159,17 +159,6 @@ static ret_t window_manager_idle_destroy_window(const idle_info_t* info) {
   return RET_OK;
 }
 
-static int compare_win(void* a, void* b) {
-  widget_t* win = WIDGET(b);
-  widget_t* widget = WIDGET(a);
-
-  if (widget_get_window(widget) == win) {
-    return 0;
-  } else {
-    return 1;
-  }
-}
-
 ret_t window_manager_close_window(widget_t* widget, widget_t* window) {
   ret_t ret = RET_OK;
   window_manager_t* wm = WINDOW_MANAGER(widget);
@@ -182,7 +171,11 @@ ret_t window_manager_close_window(widget_t* widget, widget_t* window) {
   if (widget->key_target == window) {
     widget->key_target = NULL;
   }
-  array_remove_all(&(wm->grab_widgets), compare_win, window, NULL);
+  if (wm->grab_widget != NULL) {
+    if (widget_get_window(wm->grab_widget) == window) {
+      wm->grab_widget = NULL;
+    }
+  }
 
   if (wm->animator) {
     wm->pending_close_window = window;
@@ -199,38 +192,30 @@ ret_t window_manager_close_window(widget_t* widget, widget_t* window) {
 }
 
 widget_t* window_manager_find_target(widget_t* widget, xy_t x, xy_t y) {
-  uint32_t i = 0;
-  uint32_t n = 0;
   point_t p = {x, y};
   window_manager_t* wm = WINDOW_MANAGER(widget);
   return_value_if_fail(widget != NULL, NULL);
 
-  if (wm->grab_widgets.size > 0) {
-    widget_t* target = WIDGET(wm->grab_widgets.elms[wm->grab_widgets.size - 1]);
+  if (wm->grab_widget != NULL) {
+    widget_t* target = wm->grab_widget;
     /*log_debug("target=%s\n", target->vt->type_name);*/
     return target;
   }
 
   widget_to_local(widget, &p);
-  if (widget->children != NULL && widget->children->size > 0) {
-    xy_t xx = p.x;
-    xy_t yy = p.y;
-    n = widget->children->size;
-    for (i = n; i > 0; i--) {
-      widget_t* iter = (widget_t*)(widget->children->elms[i - 1]);
-      xy_t r = iter->x + iter->w;
-      xy_t b = iter->y + iter->h;
+  WIDGET_FOR_EACH_CHILD_BEGIN_R(widget, iter, i)
+  xy_t r = iter->x + iter->w;
+  xy_t b = iter->y + iter->h;
 
-      if (xx >= iter->x && yy >= iter->y && xx <= r && yy <= b) {
-        return iter;
-      }
-
-      if (iter->type == WIDGET_NORMAL_WINDOW || iter->type == WIDGET_DIALOG) {
-        return iter;
-      }
-    }
+  if (p.x >= iter->x && p.y >= iter->y && p.x <= r && p.y <= b) {
+    return iter;
   }
 
+  if (iter->type == WIDGET_NORMAL_WINDOW || iter->type == WIDGET_DIALOG) {
+    return iter;
+  }
+  WIDGET_FOR_EACH_CHILD_END()
+
   return NULL;
 }
 
@@ -371,16 +356,21 @@ static ret_t window_manager_grab(widget_t* widget, widget_t* child) {
   window_manager_t* wm = WINDOW_MANAGER(widget);
   return_value_if_fail(widget != NULL && child != NULL, RET_BAD_PARAMS);
 
-  log_debug("grab: %s\n", child->vt->type_name);
-  return array_push(&(wm->grab_widgets), child);
+  wm->grab_widget = child;
+
+  return RET_OK;
 }
 
 static ret_t window_manager_ungrab(widget_t* widget, widget_t* child) {
   window_manager_t* wm = WINDOW_MANAGER(widget);
   return_value_if_fail(widget != NULL && child != NULL, RET_BAD_PARAMS);
 
-  log_debug("ungrab: %s\n", child->vt->type_name);
-  return array_remove_all(&(wm->grab_widgets), NULL, child, NULL);
+  if (wm->grab_widget == child) {
+    wm->grab_widget = NULL;
+    log_debug("ungrab: %s\n", child->vt->type_name);
+  }
+
+  return RET_OK;
 }
 
 static ret_t window_manager_invalidate(widget_t* widget, rect_t* r) {
@@ -393,19 +383,13 @@ static ret_t window_manager_invalidate(widget_t* widget, rect_t* r) {
 }
 
 int32_t window_manager_find_top_window_index(widget_t* widget) {
-  int32_t i = 0;
-  int32_t nr = 0;
   return_value_if_fail(widget != NULL, -1);
 
-  if (widget->children != NULL && widget->children->size > 0) {
-    nr = widget->children->size;
-    for (i = nr - 1; i >= 0; i--) {
-      widget_t* iter = (widget_t*)(widget->children->elms[i]);
-      if (iter->type == WIDGET_NORMAL_WINDOW) {
-        return i;
-      }
-    }
+  WIDGET_FOR_EACH_CHILD_BEGIN_R(widget, iter, i)
+  if (iter->type == WIDGET_NORMAL_WINDOW) {
+    return i;
   }
+  WIDGET_FOR_EACH_CHILD_END();
 
   return -1;
 }
@@ -476,7 +460,6 @@ widget_t* window_manager_init(window_manager_t* wm) {
 
   w->vt = &s_wm_vtable;
   widget_init(w, NULL, WIDGET_WINDOW_MANAGER);
-  array_init(&(wm->grab_widgets), 5);
 
 #ifdef WITH_DYNAMIC_TR
   locale_on(locale(), EVT_LOCALE_CHANGED, wm_on_locale_changed, wm);
diff --git a/src/base/window_manager.h b/src/base/window_manager.h
index 5878f7512..7dec226e7 100644
--- a/src/base/window_manager.h
+++ b/src/base/window_manager.h
@@ -36,7 +36,7 @@ BEGIN_C_DECLS
 typedef struct _window_manager_t {
   widget_t widget;
 
-  array_t grab_widgets;
+  widget_t* grab_widget;
   rect_t dirty_rect;
   rect_t last_dirty_rect;
 
diff --git a/tests/widget_test.cc b/tests/widget_test.cc
index 0a99f3aea..c2bb18456 100644
--- a/tests/widget_test.cc
+++ b/tests/widget_test.cc
@@ -287,3 +287,15 @@ TEST(Widget, prop) {
 
   widget_destroy(w);
 }
+
+TEST(Widget, dirty) {
+  widget_t* w = window_create(NULL, 0, 0, 400, 300);
+  widget_t* b1 = button_create(w, 0, 0, 100, 100);
+  widget_invalidate(w, NULL);
+  ASSERT_EQ(w->dirty, TRUE);
+  ASSERT_EQ(b1->dirty, TRUE);
+  widget_destroy_children(w);
+  ASSERT_EQ(w->children->size, 0);
+
+  widget_destroy(w);
+}