diff --git a/demos/benchmark/lv_demo_benchmark.c b/demos/benchmark/lv_demo_benchmark.c
index 4c49a1dc5..63e30bad1 100644
--- a/demos/benchmark/lv_demo_benchmark.c
+++ b/demos/benchmark/lv_demo_benchmark.c
@@ -89,7 +89,7 @@ LV_FONT_DECLARE(lv_font_benchmark_montserrat_16_compr_az);
 LV_FONT_DECLARE(lv_font_benchmark_montserrat_28_compr_az);
 
 static void monitor_cb(lv_disp_drv_t * drv, uint32_t time, uint32_t px);
-static void scene_next_task_cb(lv_timer_t * timer);
+static void next_scene_timer_cb(lv_timer_t * timer);
 static void rect_create(lv_style_t * style);
 static void img_create(lv_style_t * style, const void * src, bool rotate, bool zoom, bool aa);
 static void txt_create(lv_style_t * style);
@@ -636,7 +636,7 @@ static lv_obj_t * scene_bg;
 static lv_obj_t * title;
 static lv_obj_t * subtitle;
 static uint32_t rnd_act;
-
+static lv_timer_t * next_scene_timer;
 
 static const uint32_t rnd_map[] = {
     0xbd13204f, 0x67d8167f, 0x20211c99, 0xb0a7cc05,
@@ -708,9 +708,21 @@ void lv_demo_benchmark(void)
     benchmark_init();
 
     /*Manually start scenes*/
-    scene_next_task_cb(NULL);
+    next_scene_timer_cb(NULL);
 }
 
+void lv_demo_benchmark_close(void)
+{
+    if(next_scene_timer) lv_timer_del(next_scene_timer);
+    next_scene_timer = NULL;
+
+    lv_anim_del(NULL, NULL);
+
+    lv_style_reset(&style_common);
+
+    lv_obj_clean(lv_scr_act());
+
+}
 
 void lv_demo_benchmark_run_scene(int_fast16_t scene_no)
 {
@@ -973,11 +985,13 @@ static void report_cb(lv_timer_t * timer)
     }
 }
 
-static void scene_next_task_cb(lv_timer_t * timer)
+static void next_scene_timer_cb(lv_timer_t * timer)
 {
     LV_UNUSED(timer);
     lv_obj_clean(scene_bg);
 
+    next_scene_timer = NULL;
+
     if(opa_mode) {
         if(scene_act >= 0) {
             if(scenes[scene_act].time_sum_opa == 0) scenes[scene_act].time_sum_opa = 1;
@@ -1014,8 +1028,8 @@ static void scene_next_task_cb(lv_timer_t * timer)
 
         rnd_reset();
         scenes[scene_act].create_cb();
-        lv_timer_t * t = lv_timer_create(scene_next_task_cb, SCENE_TIME, NULL);
-        lv_timer_set_repeat_count(t, 1);
+        next_scene_timer = lv_timer_create(next_scene_timer_cb, SCENE_TIME, NULL);
+        lv_timer_set_repeat_count(next_scene_timer, 1);
 
     }
     /*Ready*/
diff --git a/demos/benchmark/lv_demo_benchmark.h b/demos/benchmark/lv_demo_benchmark.h
index 6a0a4f649..71a7589aa 100644
--- a/demos/benchmark/lv_demo_benchmark.h
+++ b/demos/benchmark/lv_demo_benchmark.h
@@ -30,6 +30,8 @@ typedef void finished_cb_t(void);
  **********************/
 void lv_demo_benchmark(void);
 
+void lv_demo_benchmark_close(void);
+
 void lv_demo_benchmark_run_scene(int_fast16_t scene_no);
 
 void lv_demo_benchmark_set_finished_cb(finished_cb_t * finished_cb);
diff --git a/demos/keypad_encoder/lv_demo_keypad_encoder.c b/demos/keypad_encoder/lv_demo_keypad_encoder.c
index fdb9b94f8..0f4006e0d 100644
--- a/demos/keypad_encoder/lv_demo_keypad_encoder.c
+++ b/demos/keypad_encoder/lv_demo_keypad_encoder.c
@@ -46,8 +46,11 @@ static lv_obj_t * t2;
 
 void lv_demo_keypad_encoder(void)
 {
-    g = lv_group_create();
-    lv_group_set_default(g);
+    g = lv_group_get_default();
+    if(g == NULL) {
+        g = lv_group_create();
+        lv_group_set_default(g);
+    }
 
     lv_indev_t * cur_drv = NULL;
     for(;;) {
@@ -76,6 +79,12 @@ void lv_demo_keypad_encoder(void)
     msgbox_create();
 }
 
+void lv_demo_keypad_encoder_close(void)
+{
+    lv_obj_clean(lv_scr_act());
+    lv_obj_clean(lv_layer_top());
+}
+
 /**********************
  *   STATIC FUNCTIONS
  **********************/
diff --git a/demos/keypad_encoder/lv_demo_keypad_encoder.h b/demos/keypad_encoder/lv_demo_keypad_encoder.h
index c509d662e..1916670bc 100644
--- a/demos/keypad_encoder/lv_demo_keypad_encoder.h
+++ b/demos/keypad_encoder/lv_demo_keypad_encoder.h
@@ -27,6 +27,7 @@ extern "C" {
  * GLOBAL PROTOTYPES
  **********************/
 void lv_demo_keypad_encoder(void);
+void lv_demo_keypad_encoder_close(void);
 
 /**********************
  *      MACROS
diff --git a/demos/music/lv_demo_music.c b/demos/music/lv_demo_music.c
index cb72ed162..25bfd95f8 100644
--- a/demos/music/lv_demo_music.c
+++ b/demos/music/lv_demo_music.c
@@ -103,6 +103,12 @@ static const uint32_t time_list[] = {
     2 * 60 + 19,
 };
 
+#if LV_DEMO_MUSIC_AUTO_PLAY
+static lv_timer_t * auto_step_timer;
+#endif
+
+static lv_color_t original_screen_bg_color;
+
 /**********************
  *      MACROS
  **********************/
@@ -113,16 +119,33 @@ static const uint32_t time_list[] = {
 
 void lv_demo_music(void)
 {
+    original_screen_bg_color = lv_obj_get_style_bg_color(lv_scr_act(), 0);
     lv_obj_set_style_bg_color(lv_scr_act(), lv_color_hex(0x343247), 0);
 
     list = _lv_demo_music_list_create(lv_scr_act());
     ctrl = _lv_demo_music_main_create(lv_scr_act());
 
 #if LV_DEMO_MUSIC_AUTO_PLAY
-    lv_timer_create(auto_step_cb, 1000, NULL);
+    auto_step_timer = lv_timer_create(auto_step_cb, 1000, NULL);
 #endif
 }
 
+void lv_demo_music_close(void)
+{
+    /*Delete all aniamtions*/
+    lv_anim_del(NULL, NULL);
+
+#if LV_DEMO_MUSIC_AUTO_PLAY
+    lv_timer_del(auto_step_timer);
+#endif
+    _lv_demo_music_list_close();
+    _lv_demo_music_main_close();
+
+    lv_obj_clean(lv_scr_act());
+
+    lv_obj_set_style_bg_color(lv_scr_act(), original_screen_bg_color, 0);
+}
+
 const char * _lv_demo_music_get_title(uint32_t track_id)
 {
     if(track_id >= sizeof(title_list) / sizeof(title_list[0])) return NULL;
diff --git a/demos/music/lv_demo_music.h b/demos/music/lv_demo_music.h
index 82917fb52..3c393d66f 100644
--- a/demos/music/lv_demo_music.h
+++ b/demos/music/lv_demo_music.h
@@ -36,6 +36,8 @@ extern "C" {
  **********************/
 
 void lv_demo_music(void);
+void lv_demo_music_close(void);
+
 const char * _lv_demo_music_get_title(uint32_t track_id);
 const char * _lv_demo_music_get_artist(uint32_t track_id);
 const char * _lv_demo_music_get_genre(uint32_t track_id);
diff --git a/demos/music/lv_demo_music_list.c b/demos/music/lv_demo_music_list.c
index 88e79ecab..942baeb24 100644
--- a/demos/music/lv_demo_music_list.c
+++ b/demos/music/lv_demo_music_list.c
@@ -130,6 +130,19 @@ lv_obj_t * _lv_demo_music_list_create(lv_obj_t * parent)
     return list;
 }
 
+
+void _lv_demo_music_list_close(void)
+{
+    lv_style_reset(&style_scrollbar);
+    lv_style_reset(&style_btn);
+    lv_style_reset(&style_btn_pr);
+    lv_style_reset(&style_btn_chk);
+    lv_style_reset(&style_btn_dis);
+    lv_style_reset(&style_title);
+    lv_style_reset(&style_artist);
+    lv_style_reset(&style_time);
+}
+
 void _lv_demo_music_list_btn_check(uint32_t track_id, bool state)
 {
     lv_obj_t * btn = lv_obj_get_child(list, track_id);
diff --git a/demos/music/lv_demo_music_list.h b/demos/music/lv_demo_music_list.h
index 48e6e1704..d03c6d178 100644
--- a/demos/music/lv_demo_music_list.h
+++ b/demos/music/lv_demo_music_list.h
@@ -28,6 +28,8 @@ extern "C" {
  * GLOBAL PROTOTYPES
  **********************/
 lv_obj_t * _lv_demo_music_list_create(lv_obj_t * parent);
+void _lv_demo_music_list_close(void);
+
 void _lv_demo_music_list_btn_check(uint32_t track_id, bool state);
 
 /**********************
diff --git a/demos/music/lv_demo_music_main.c b/demos/music/lv_demo_music_main.c
index f7bc4b8fe..415af8155 100644
--- a/demos/music/lv_demo_music_main.c
+++ b/demos/music/lv_demo_music_main.c
@@ -60,7 +60,7 @@ static void prev_click_event_cb(lv_event_t * e);
 static void next_click_event_cb(lv_event_t * e);
 static void timer_cb(lv_timer_t * t);
 static void track_load(uint32_t id);
-static void stop_start_anim(lv_timer_t * t);
+static void stop_start_anim_timer_cb(lv_timer_t * t);
 static void spectrum_end_cb(lv_anim_t * a);
 static void album_fade_anim_cb(void * var, int32_t v);
 static int32_t get_cos(int32_t deg, int32_t a);
@@ -84,6 +84,7 @@ static uint32_t spectrum_lane_ofs_start = 0;
 static uint32_t bar_rot = 0;
 static uint32_t time_act;
 static lv_timer_t  * sec_counter_timer;
+static lv_timer_t * stop_start_anim_timer;
 static const lv_font_t * font_small;
 static const lv_font_t * font_large;
 static uint32_t track_id;
@@ -232,8 +233,8 @@ lv_obj_t * _lv_demo_music_main_create(lv_obj_t * parent)
 
     start_anim = true;
 
-    lv_timer_t * timer = lv_timer_create(stop_start_anim, INTRO_TIME + 6000, NULL);
-    lv_timer_set_repeat_count(timer, 1);
+    stop_start_anim_timer = lv_timer_create(stop_start_anim_timer_cb, INTRO_TIME + 6000, NULL);
+    lv_timer_set_repeat_count(stop_start_anim_timer, 1);
 
     lv_anim_init(&a);
     lv_anim_set_path_cb(&a, lv_anim_path_bounce);
@@ -292,6 +293,12 @@ lv_obj_t * _lv_demo_music_main_create(lv_obj_t * parent)
     return main_cont;
 }
 
+void _lv_demo_music_main_close(void)
+{
+    if(stop_start_anim_timer) lv_timer_del(stop_start_anim_timer);
+    lv_timer_del(sec_counter_timer);
+}
+
 void _lv_demo_music_album_next(bool next)
 {
     uint32_t id = track_id;
@@ -990,10 +997,11 @@ static void spectrum_end_cb(lv_anim_t * a)
 }
 
 
-static void stop_start_anim(lv_timer_t * t)
+static void stop_start_anim_timer_cb(lv_timer_t * t)
 {
     LV_UNUSED(t);
     start_anim = false;
+    stop_start_anim_timer = NULL;
     lv_obj_refresh_ext_draw_size(spectrum_obj);
 }
 
diff --git a/demos/music/lv_demo_music_main.h b/demos/music/lv_demo_music_main.h
index a2cf93994..04e8a7fbc 100644
--- a/demos/music/lv_demo_music_main.h
+++ b/demos/music/lv_demo_music_main.h
@@ -28,6 +28,8 @@ extern "C" {
  * GLOBAL PROTOTYPES
  **********************/
 lv_obj_t * _lv_demo_music_main_create(lv_obj_t * parent);
+void _lv_demo_music_main_close(void);
+
 void _lv_demo_music_play(uint32_t id);
 void _lv_demo_music_resume(void);
 void _lv_demo_music_pause(void);
diff --git a/demos/stress/lv_demo_stress.c b/demos/stress/lv_demo_stress.c
index b24744307..f6e708935 100644
--- a/demos/stress/lv_demo_stress.c
+++ b/demos/stress/lv_demo_stress.c
@@ -25,7 +25,7 @@ static void msgbox_del(lv_timer_t * tmr);
 static void set_y_anim(void * obj, int32_t v);
 static void set_width_anim(void * obj, int32_t v);
 static void arc_set_end_angle_anim(void * obj, int32_t v);
-static void obj_test_task_cb(lv_timer_t * tmr);
+static void obj_test_timer_cb(lv_timer_t * tmr);
 
 /**********************
  *  STATIC VARIABLES
@@ -34,6 +34,8 @@ static lv_obj_t * main_page;
 static lv_obj_t * ta;
 static const char * mbox_btns[] = {"Ok", "Cancel", ""};
 static uint32_t mem_free_start = 0;
+static lv_timer_t * obj_test_timer;
+
 /**********************
  *      MACROS
  **********************/
@@ -45,14 +47,21 @@ static uint32_t mem_free_start = 0;
 void lv_demo_stress(void)
 {
     LV_LOG_USER("Starting stress test. (< 100 bytes permanent memory leak is normal due to fragmentation)");
-    lv_timer_create(obj_test_task_cb, LV_DEMO_STRESS_TIME_STEP, NULL);
+    obj_test_timer = lv_timer_create(obj_test_timer_cb, LV_DEMO_STRESS_TIME_STEP, NULL);
+}
+
+void lv_demo_stress_close(void)
+{
+    lv_timer_del(obj_test_timer);
+    lv_obj_clean(lv_scr_act());
+    lv_obj_clean(lv_layer_top());
 }
 
 /**********************
  *   STATIC FUNCTIONS
  **********************/
 
-static void obj_test_task_cb(lv_timer_t * tmr)
+static void obj_test_timer_cb(lv_timer_t * tmr)
 {
     (void) tmr;    /*Unused*/
     static int16_t state = -1;
diff --git a/demos/stress/lv_demo_stress.h b/demos/stress/lv_demo_stress.h
index f71836662..aacc9e1cc 100644
--- a/demos/stress/lv_demo_stress.h
+++ b/demos/stress/lv_demo_stress.h
@@ -30,6 +30,8 @@ extern "C" {
  **********************/
 void lv_demo_stress(void);
 
+void lv_demo_stress_close(void);
+
 /**********************
  *      MACROS
  **********************/
diff --git a/demos/widgets/lv_demo_widgets.c b/demos/widgets/lv_demo_widgets.c
index 839b999c0..44567e420 100644
--- a/demos/widgets/lv_demo_widgets.c
+++ b/demos/widgets/lv_demo_widgets.c
@@ -86,6 +86,8 @@ static uint32_t session_desktop = 1000;
 static uint32_t session_tablet = 1000;
 static uint32_t session_mobile = 1000;
 
+static lv_timer_t * meter2_timer;
+
 /**********************
  *      MACROS
  **********************/
@@ -196,6 +198,22 @@ void lv_demo_widgets(void)
     color_changer_create(tv);
 }
 
+void lv_demo_widgets_close(void)
+{
+    /*Delete all animation*/
+    lv_anim_del(NULL, NULL);
+
+    lv_timer_del(meter2_timer);
+    meter2_timer = NULL;
+
+    lv_obj_clean(lv_scr_act());
+
+    lv_style_reset(&style_text_muted);
+    lv_style_reset(&style_title);
+    lv_style_reset(&style_icon);
+    lv_style_reset(&style_bullet);
+}
+
 /**********************
  *   STATIC FUNCTIONS
  **********************/
@@ -205,6 +223,7 @@ static void profile_create(lv_obj_t * parent)
     lv_obj_t * panel1 = lv_obj_create(parent);
     lv_obj_set_height(panel1, LV_SIZE_CONTENT);
 
+
     LV_IMG_DECLARE(img_demo_widgets_avatar);
     lv_obj_t * avatar = lv_img_create(panel1);
     lv_img_set_src(avatar, &img_demo_widgets_avatar);
@@ -698,7 +717,7 @@ static void analytics_create(lv_obj_t * parent)
     lv_meter_set_indicator_start_value(meter2, meter2_indic[2], 70);
     lv_meter_set_indicator_end_value(meter2, meter2_indic[2], 99);
 
-    lv_timer_create(meter2_timer_cb, 100, meter2_indic);
+    meter2_timer = lv_timer_create(meter2_timer_cb, 100, meter2_indic);
 
     meter3 = create_meter_box(parent, "Network Speed", "Low speed", "Normal Speed", "High Speed");
     if(disp_size < DISP_LARGE) lv_obj_add_flag(lv_obj_get_parent(meter3), LV_OBJ_FLAG_FLEX_IN_NEW_TRACK);
diff --git a/demos/widgets/lv_demo_widgets.h b/demos/widgets/lv_demo_widgets.h
index 66dddafc6..8d70df168 100644
--- a/demos/widgets/lv_demo_widgets.h
+++ b/demos/widgets/lv_demo_widgets.h
@@ -27,6 +27,7 @@ extern "C" {
  * GLOBAL PROTOTYPES
  **********************/
 void lv_demo_widgets(void);
+void lv_demo_widgets_close(void);
 
 /**********************
  *      MACROS
diff --git a/src/core/lv_obj.h b/src/core/lv_obj.h
index c89e46099..a6a9ac38c 100644
--- a/src/core/lv_obj.h
+++ b/src/core/lv_obj.h
@@ -188,6 +188,7 @@ typedef struct _lv_obj_t {
     uint16_t style_cnt  : 6;
     uint16_t h_layout   : 1;
     uint16_t w_layout   : 1;
+    uint16_t being_deleted   : 1;
 } lv_obj_t;
 
 
diff --git a/src/core/lv_obj_tree.c b/src/core/lv_obj_tree.c
index d3ad16ae3..dbd350a46 100644
--- a/src/core/lv_obj_tree.c
+++ b/src/core/lv_obj_tree.c
@@ -360,6 +360,8 @@ static void obj_del_core(lv_obj_t * obj)
     lv_res_t res = lv_event_send(obj, LV_EVENT_DELETE, NULL);
     if(res == LV_RES_INV) return;
 
+    obj->being_deleted = 1;
+
     /*Recursively delete the children*/
     lv_obj_t * child = lv_obj_get_child(obj, 0);
     while(child) {
diff --git a/src/extra/widgets/tabview/lv_tabview.c b/src/extra/widgets/tabview/lv_tabview.c
index b77e0be3e..edd1f749f 100755
--- a/src/extra/widgets/tabview/lv_tabview.c
+++ b/src/extra/widgets/tabview/lv_tabview.c
@@ -77,8 +77,8 @@ lv_obj_t * lv_tabview_add_tab(lv_obj_t * obj, const char * name)
 
     lv_obj_t * btns = lv_tabview_get_tab_btns(obj);
 
-    char ** old_map = tabview->map;
-    char ** new_map;
+    const char ** old_map = (const char **)tabview->map;
+    const char ** new_map;
 
     /*top or bottom dir*/
     if(tabview->tab_pos & LV_DIR_VER) {
@@ -138,6 +138,8 @@ void lv_tabview_rename_tab(lv_obj_t * obj, uint32_t id, const char * new_name)
 void lv_tabview_set_act(lv_obj_t * obj, uint32_t id, lv_anim_enable_t anim_en)
 {
     LV_ASSERT_OBJ(obj, MY_CLASS);
+    if(obj->being_deleted) return;
+
     lv_tabview_t * tabview = (lv_tabview_t *)obj;
 
     if(id >= tabview->tab_cnt) {
diff --git a/src/extra/widgets/tabview/lv_tabview.h b/src/extra/widgets/tabview/lv_tabview.h
index 388c65477..ee7d7ce41 100644
--- a/src/extra/widgets/tabview/lv_tabview.h
+++ b/src/extra/widgets/tabview/lv_tabview.h
@@ -27,7 +27,7 @@ extern "C" {
 
 typedef struct {
     lv_obj_t obj;
-    char ** map;
+    const char ** map;
     uint16_t tab_cnt;
     uint16_t tab_cur;
     lv_dir_t tab_pos;