diff --git a/docs/misc/boxmodel.png b/docs/misc/boxmodel.png
index bdd013368..0368fa99a 100644
Binary files a/docs/misc/boxmodel.png and b/docs/misc/boxmodel.png differ
diff --git a/src/core/lv_event.c b/src/core/lv_event.c
index 45c50c8d2..ff5bd6133 100644
--- a/src/core/lv_event.c
+++ b/src/core/lv_event.c
@@ -18,6 +18,16 @@
  *      TYPEDEFS
  **********************/
 
+typedef struct _lv_event_t {
+    struct _lv_obj_t * target;
+    struct _lv_obj_t * current_target;
+    lv_event_code_t code;
+    void * user_data;
+    void * param;
+    struct _lv_event_t * prev;
+    uint8_t deleted :1;
+}lv_event_t;
+
 typedef struct _lv_event_dsc_t{
     lv_event_cb_t cb;
     void * user_data;
diff --git a/src/core/lv_event.h b/src/core/lv_event.h
index 689cbc4bc..d5c5af1a6 100644
--- a/src/core/lv_event.h
+++ b/src/core/lv_event.h
@@ -81,16 +81,8 @@ typedef enum {
     _LV_EVENT_LAST                /** Number of default events*/
 }lv_event_code_t;
 
-
-typedef struct _lv_event_t {
-    struct _lv_obj_t * target;
-    struct _lv_obj_t * current_target;
-    lv_event_code_t code;
-    void * user_data;
-    void * param;
-    struct _lv_event_t * prev;
-    uint8_t deleted :1;
-}lv_event_t;
+struct _lv_event_t;
+typedef struct _lv_event_t lv_event_t;
 
 /**
  * @brief Event callback.
diff --git a/src/core/lv_group.c b/src/core/lv_group.c
index e5c9252d8..c017514b1 100644
--- a/src/core/lv_group.c
+++ b/src/core/lv_group.c
@@ -20,6 +20,26 @@
 /**********************
  *      TYPEDEFS
  **********************/
+/**
+ * Groups can be used to logically hold objects so that they can be individually focused.
+ * They are NOT for laying out objects on a screen (try `lv_cont` for that).
+ */
+typedef struct _lv_group_t {
+    lv_ll_t obj_ll;        /**< Linked list to store the objects in the group*/
+    struct _lv_obj_t ** obj_focus; /**< The object in focus*/
+
+    lv_group_focus_cb_t focus_cb;              /**< A function to call when a new object is focused (optional)*/
+#if LV_USE_USER_DATA
+    void * user_data;
+#endif
+
+    uint8_t frozen : 1;         /**< 1: can't focus to new object*/
+    uint8_t editing : 1;        /**< 1: Edit mode, 0: Navigate mode*/
+    uint8_t refocus_policy : 1; /**< 1: Focus prev if focused on deletion. 0: Focus next if focused on
+                                   deletion.*/
+    uint8_t wrap : 1;           /**< 1: Focus next/prev can wrap at end of list. 0: Focus next/prev stops at end
+                                   of list.*/
+} lv_group_t;
 
 /**********************
  *  STATIC PROTOTYPES
@@ -321,6 +341,10 @@ bool lv_group_get_wrap(lv_group_t * group)
     return group->wrap ? true : false;
 }
 
+uint32_t lv_group_get_obj_count(lv_group_t * group)
+{
+    return _lv_ll_get_len(&group->obj_ll);
+}
 /**********************
  *   STATIC FUNCTIONS
  **********************/
diff --git a/src/core/lv_group.h b/src/core/lv_group.h
index fab33343e..cc0cb4533 100644
--- a/src/core/lv_group.h
+++ b/src/core/lv_group.h
@@ -46,33 +46,16 @@ typedef uint8_t lv_key_t;
  *      TYPEDEFS
  **********************/
 struct _lv_group_t;
+typedef struct _lv_group_t lv_group_t;
+
 struct _lv_obj_t;
 
 typedef void (*lv_group_focus_cb_t)(struct _lv_group_t *);
 
-/**
- * Groups can be used to logically hold objects so that they can be individually focused.
- * They are NOT for laying out objects on a screen (try `lv_cont` for that).
- */
-typedef struct _lv_group_t {
-    lv_ll_t obj_ll;        /**< Linked list to store the objects in the group*/
-    struct _lv_obj_t ** obj_focus; /**< The object in focus*/
-
-    lv_group_focus_cb_t focus_cb;              /**< A function to call when a new object is focused (optional)*/
-#if LV_USE_USER_DATA
-    void * user_data;
-#endif
-
-    uint8_t frozen : 1;         /**< 1: can't focus to new object*/
-    uint8_t editing : 1;        /**< 1: Edit mode, 0: Navigate mode*/
-    uint8_t refocus_policy : 1; /**< 1: Focus prev if focused on deletion. 0: Focus next if focused on
-                                   deletion.*/
-    uint8_t wrap : 1;           /**< 1: Focus next/prev can wrap at end of list. 0: Focus next/prev stops at end
-                                   of list.*/
-} lv_group_t;
-
-enum { LV_GROUP_REFOCUS_POLICY_NEXT = 0, LV_GROUP_REFOCUS_POLICY_PREV = 1 };
-typedef uint8_t lv_group_refocus_policy_t;
+typedef enum {
+    LV_GROUP_REFOCUS_POLICY_NEXT = 0,
+    LV_GROUP_REFOCUS_POLICY_PREV = 1
+}lv_group_refocus_policy_t;
 
 /**********************
  * GLOBAL PROTOTYPES
@@ -212,11 +195,18 @@ bool lv_group_get_editing(const lv_group_t * group);
 
 /**
  * Get whether focus next/prev will allow wrapping from first->last or last->first object.
- * @param group             pointer to group
+ * @param group         pointer to group
  * @param               en true: wrapping enabled; false: wrapping disabled
  */
 bool lv_group_get_wrap(lv_group_t * group);
 
+/**
+ * Get the number of object in the group
+ * @param group         pointer to a group
+ * @return              number of objects in the group
+ */
+uint32_t lv_group_get_obj_count(lv_group_t * group);
+
 /**********************
  *      MACROS
  **********************/
diff --git a/src/core/lv_indev.c b/src/core/lv_indev.c
index 55b10898e..2e16b8e5f 100644
--- a/src/core/lv_indev.c
+++ b/src/core/lv_indev.c
@@ -35,12 +35,12 @@ static void indev_pointer_proc(lv_indev_t * i, lv_indev_data_t * data);
 static void indev_keypad_proc(lv_indev_t * i, lv_indev_data_t * data);
 static void indev_encoder_proc(lv_indev_t * i, lv_indev_data_t * data);
 static void indev_button_proc(lv_indev_t * i, lv_indev_data_t * data);
-static void indev_proc_press(lv_indev_proc_t * proc);
-static void indev_proc_release(lv_indev_proc_t * proc);
+static void indev_proc_press(_lv_indev_proc_t * proc);
+static void indev_proc_release(_lv_indev_proc_t * proc);
 static void indev_proc_reset_query_handler(lv_indev_t * indev);
-static void indev_click_focus(lv_indev_proc_t * proc);
-static void indev_gesture(lv_indev_proc_t * proc);
-static bool indev_reset_check(lv_indev_proc_t * proc);
+static void indev_click_focus(_lv_indev_proc_t * proc);
+static void indev_gesture(_lv_indev_proc_t * proc);
+static bool indev_reset_check(_lv_indev_proc_t * proc);
 
 /**********************
  *  STATIC VARIABLES
@@ -595,7 +595,7 @@ static void indev_encoder_proc(lv_indev_t * i, lv_indev_data_t * data)
                 /*On enter long press toggle edit mode.*/
                 if(editable) {
                     /*Don't leave edit mode if there is only one object (nowhere to navigate)*/
-                    if(_lv_ll_get_len(&g->obj_ll) > 1) {
+                    if(lv_group_get_obj_count(g) > 1) {
                         lv_group_set_editing(g, lv_group_get_editing(g) ? false : true); /*Toggle edit mode on long press*/
                         lv_obj_clear_state(indev_obj_act, LV_STATE_PRESSED);    /*Remove the pressed state manually*/
                     }
@@ -654,9 +654,9 @@ static void indev_encoder_proc(lv_indev_t * i, lv_indev_data_t * data)
 
             }
             /*An object is being edited and the button is released.*/
-            else if(g->editing) {
+            else if(lv_group_get_editing(g)) {
                 /*Ignore long pressed enter release because it comes from mode switch*/
-                if(!i->proc.long_pr_sent || _lv_ll_get_len(&g->obj_ll) <= 1) {
+                if(!i->proc.long_pr_sent || lv_group_get_obj_count(g) <= 1) {
                     lv_event_send(indev_obj_act, LV_EVENT_RELEASED, indev_act);
                     if(indev_reset_check(&i->proc)) return;
 
@@ -674,7 +674,7 @@ static void indev_encoder_proc(lv_indev_t * i, lv_indev_data_t * data)
             }
             /*If the focused object is editable and now in navigate mode then on enter switch edit
                mode*/
-            else if(editable && !g->editing && !i->proc.long_pr_sent) {
+            else if(editable && !lv_group_get_editing(g) && !i->proc.long_pr_sent) {
                 lv_group_set_editing(g, true); /*Set edit mode*/
             }
         }
@@ -765,7 +765,7 @@ static void indev_button_proc(lv_indev_t * i, lv_indev_data_t * data)
  * @param indev pointer to an input device 'proc'
  * @return LV_RES_OK: no indev reset required; LV_RES_INV: indev reset is required
  */
-static void indev_proc_press(lv_indev_proc_t * proc)
+static void indev_proc_press(_lv_indev_proc_t * proc)
 {
     LV_LOG_INFO("pressed at x:%d y:%d", proc->types.pointer.act_point.x, proc->types.pointer.act_point.y);
     indev_obj_act = proc->types.pointer.act_obj;
@@ -901,7 +901,7 @@ static void indev_proc_press(lv_indev_proc_t * proc)
  * Process the released state of LV_INDEV_TYPE_POINTER input devices
  * @param proc pointer to an input device 'proc'
  */
-static void indev_proc_release(lv_indev_proc_t * proc)
+static void indev_proc_release(_lv_indev_proc_t * proc)
 {
     if(proc->wait_until_release != 0) {
         proc->types.pointer.act_obj  = NULL;
@@ -978,7 +978,7 @@ static void indev_proc_reset_query_handler(lv_indev_t * indev)
  * Handle focus/defocus on click for POINTER input devices
  * @param proc pointer to the state of the indev
  */
-static void indev_click_focus(lv_indev_proc_t * proc)
+static void indev_click_focus(_lv_indev_proc_t * proc)
 {
     /*Handle click focus*/
     lv_obj_t * obj_to_focus = indev_obj_act;
@@ -1047,7 +1047,7 @@ static void indev_click_focus(lv_indev_proc_t * proc)
 * Handle the gesture of indev_proc_p->types.pointer.act_obj
 * @param indev pointer to a input device state
 */
-void indev_gesture(lv_indev_proc_t * proc)
+void indev_gesture(_lv_indev_proc_t * proc)
 {
 
     if(proc->types.pointer.scroll_obj) return;
@@ -1100,7 +1100,7 @@ void indev_gesture(lv_indev_proc_t * proc)
  * @param proc pointer to an input device 'proc'
  * @return true if indev query should be immediately truncated.
  */
-static bool indev_reset_check(lv_indev_proc_t * proc)
+static bool indev_reset_check(_lv_indev_proc_t * proc)
 {
     if(proc->reset_query) {
         indev_obj_act = NULL;
diff --git a/src/core/lv_indev_scroll.c b/src/core/lv_indev_scroll.c
index efd7cf2d0..8cefbe6fd 100644
--- a/src/core/lv_indev_scroll.c
+++ b/src/core/lv_indev_scroll.c
@@ -21,13 +21,13 @@
 /**********************
  *  STATIC PROTOTYPES
  **********************/
-static lv_obj_t * find_scroll_obj(lv_indev_proc_t * proc);
-static void init_scroll_limits(lv_indev_proc_t * proc);
+static lv_obj_t * find_scroll_obj(_lv_indev_proc_t * proc);
+static void init_scroll_limits(_lv_indev_proc_t * proc);
 static lv_coord_t find_snap_point_x(const lv_obj_t * obj, lv_coord_t min, lv_coord_t max, lv_coord_t ofs);
 static lv_coord_t find_snap_point_y(const lv_obj_t * obj, lv_coord_t min, lv_coord_t max, lv_coord_t ofs);
-static void scroll_limit_diff(lv_indev_proc_t * proc, lv_coord_t * diff_x, lv_coord_t * diff_y);
-static lv_coord_t scroll_throw_predict_y(lv_indev_proc_t * proc);
-static lv_coord_t scroll_throw_predict_x(lv_indev_proc_t * proc);
+static void scroll_limit_diff(_lv_indev_proc_t * proc, lv_coord_t * diff_x, lv_coord_t * diff_y);
+static lv_coord_t scroll_throw_predict_y(_lv_indev_proc_t * proc);
+static lv_coord_t scroll_throw_predict_x(_lv_indev_proc_t * proc);
 static lv_coord_t elastic_diff(lv_obj_t * scroll_obj, lv_coord_t diff, lv_coord_t scroll_start, lv_coord_t scroll_end, lv_dir_t dir);
 
 /**********************
@@ -42,7 +42,7 @@ static lv_coord_t elastic_diff(lv_obj_t * scroll_obj, lv_coord_t diff, lv_coord_
  *   GLOBAL FUNCTIONS
  **********************/
 
-void _lv_indev_scroll_handler(lv_indev_proc_t * proc)
+void _lv_indev_scroll_handler(_lv_indev_proc_t * proc)
 {
     lv_obj_t * scroll_obj = proc->types.pointer.scroll_obj;
     /*If there is no scroll object yet try to find one*/
@@ -91,7 +91,7 @@ void _lv_indev_scroll_handler(lv_indev_proc_t * proc)
 }
 
 
-void _lv_indev_scroll_throw_handler(lv_indev_proc_t * proc)
+void _lv_indev_scroll_throw_handler(_lv_indev_proc_t * proc)
 {
     lv_obj_t * scroll_obj = proc->types.pointer.scroll_obj;
     if(scroll_obj == NULL) return;
@@ -236,7 +236,7 @@ void lv_indev_scroll_get_snap_dist(lv_obj_t * obj, lv_point_t * p)
  *   STATIC FUNCTIONS
  **********************/
 
-static lv_obj_t * find_scroll_obj(lv_indev_proc_t * proc)
+static lv_obj_t * find_scroll_obj(_lv_indev_proc_t * proc)
 {
     lv_obj_t * obj_candidate = NULL;
     lv_dir_t dir_candidate = LV_DIR_NONE;
@@ -341,7 +341,7 @@ static lv_obj_t * find_scroll_obj(lv_indev_proc_t * proc)
     return obj_candidate;
 }
 
-static void init_scroll_limits(lv_indev_proc_t * proc)
+static void init_scroll_limits(_lv_indev_proc_t * proc)
 {
     lv_obj_t * obj = proc->types.pointer.scroll_obj;
     /*If there no STOP allow scrolling anywhere*/
@@ -508,7 +508,7 @@ static lv_coord_t find_snap_point_y(const lv_obj_t * obj, lv_coord_t min, lv_coo
     return dist == LV_COORD_MAX ? 0 : -dist;
 }
 
-static void scroll_limit_diff(lv_indev_proc_t * proc, lv_coord_t * diff_x, lv_coord_t * diff_y)
+static void scroll_limit_diff(_lv_indev_proc_t * proc, lv_coord_t * diff_x, lv_coord_t * diff_y)
 {
     if(diff_y) {
         if(proc->types.pointer.scroll_sum.y + *diff_y < proc->types.pointer.scroll_area.y1) {
@@ -533,7 +533,7 @@ static void scroll_limit_diff(lv_indev_proc_t * proc, lv_coord_t * diff_x, lv_co
 
 
 
-static lv_coord_t scroll_throw_predict_y(lv_indev_proc_t * proc)
+static lv_coord_t scroll_throw_predict_y(_lv_indev_proc_t * proc)
 {
     lv_coord_t y =  proc->types.pointer.scroll_throw_vect.y;
     lv_coord_t move = 0;
@@ -549,7 +549,7 @@ static lv_coord_t scroll_throw_predict_y(lv_indev_proc_t * proc)
 }
 
 
-static lv_coord_t scroll_throw_predict_x(lv_indev_proc_t * proc)
+static lv_coord_t scroll_throw_predict_x(_lv_indev_proc_t * proc)
 {
     lv_coord_t x =  proc->types.pointer.scroll_throw_vect.x;
     lv_coord_t move = 0;
diff --git a/src/core/lv_indev_scroll.h b/src/core/lv_indev_scroll.h
index 83f6aed91..76c64d176 100644
--- a/src/core/lv_indev_scroll.h
+++ b/src/core/lv_indev_scroll.h
@@ -31,13 +31,13 @@ extern "C" {
  * Handle scrolling. Called by LVGL during input device processing
  * @param proc      pointer to an input device's proc field
  */
-void _lv_indev_scroll_handler(lv_indev_proc_t * proc);
+void _lv_indev_scroll_handler(_lv_indev_proc_t * proc);
 
 /**
  * Handle throwing after scrolling. Called by LVGL during input device processing
  * @param proc      pointer to an input device's proc field
  */
-void _lv_indev_scroll_throw_handler(lv_indev_proc_t * proc);
+void _lv_indev_scroll_throw_handler(_lv_indev_proc_t * proc);
 
 /**
  * Predict where would a scroll throw end
diff --git a/src/draw/lv_draw_label.h b/src/draw/lv_draw_label.h
index 930a89ef7..fb71210d5 100644
--- a/src/draw/lv_draw_label.h
+++ b/src/draw/lv_draw_label.h
@@ -51,7 +51,7 @@ typedef struct {
  * all the previous characters needs to be checked to calculate the positions.
  * This structure stores an earlier (e.g. at -1000 px) coordinate and the index of that line.
  * Therefore the calculations can start from here.*/
-typedef struct {
+typedef struct _lv_draw_label_hint_t {
     /** Index of the line at `y` coordinate*/
     int32_t line_start;
 
diff --git a/src/draw/lv_img_decoder.c b/src/draw/lv_img_decoder.c
index 4040a1f2c..0bf13831a 100644
--- a/src/draw/lv_img_decoder.c
+++ b/src/draw/lv_img_decoder.c
@@ -21,6 +21,17 @@
 /**********************
  *      TYPEDEFS
  **********************/
+typedef struct _lv_img_decoder {
+    lv_img_decoder_info_f_t info_cb;
+    lv_img_decoder_open_f_t open_cb;
+    lv_img_decoder_read_line_f_t read_line_cb;
+    lv_img_decoder_close_f_t close_cb;
+
+#if LV_USE_USER_DATA
+    void * user_data;
+#endif
+} lv_img_decoder_t;
+
 typedef struct {
     lv_fs_file_t f;
     lv_color_t * palette;
diff --git a/src/draw/lv_img_decoder.h b/src/draw/lv_img_decoder.h
index 6c852eae4..01e28342f 100644
--- a/src/draw/lv_img_decoder.h
+++ b/src/draw/lv_img_decoder.h
@@ -43,6 +43,7 @@ typedef uint8_t lv_img_src_t;
 /*Decoder function definitions*/
 
 struct _lv_img_decoder;
+typedef struct _lv_img_decoder lv_img_decoder_t;
 struct _lv_img_decoder_dsc;
 
 /**
@@ -83,17 +84,6 @@ typedef lv_res_t (*lv_img_decoder_read_line_f_t)(struct _lv_img_decoder * decode
  */
 typedef void (*lv_img_decoder_close_f_t)(struct _lv_img_decoder * decoder, struct _lv_img_decoder_dsc * dsc);
 
-typedef struct _lv_img_decoder {
-    lv_img_decoder_info_f_t info_cb;
-    lv_img_decoder_open_f_t open_cb;
-    lv_img_decoder_read_line_f_t read_line_cb;
-    lv_img_decoder_close_f_t close_cb;
-
-#if LV_USE_USER_DATA
-    void * user_data;
-#endif
-} lv_img_decoder_t;
-
 /**Describe an image decoding session. Stores data about the decoding*/
 typedef struct _lv_img_decoder_dsc {
     /**The decoder which was able to open the image source*/
diff --git a/src/hal/lv_hal_disp.h b/src/hal/lv_hal_disp.h
index 5d0e61d7b..1e3214f53 100644
--- a/src/hal/lv_hal_disp.h
+++ b/src/hal/lv_hal_disp.h
@@ -46,7 +46,7 @@ struct _lv_theme_t;
 /**
  * Structure for holding display buffer information.
  */
-typedef struct {
+typedef struct _lv_disp_draw_buf_t{
     void * buf1; /**< First display buffer.*/
     void * buf2; /**< Second display buffer.*/
 
diff --git a/src/hal/lv_hal_indev.h b/src/hal/lv_hal_indev.h
index d52b0e2df..5cdfe243f 100644
--- a/src/hal/lv_hal_indev.h
+++ b/src/hal/lv_hal_indev.h
@@ -168,13 +168,13 @@ typedef struct _lv_indev_proc_t {
 
     uint32_t pr_timestamp;         /**< Pressed time stamp*/
     uint32_t longpr_rep_timestamp; /**< Long press repeat time stamp*/
-} lv_indev_proc_t;
+} _lv_indev_proc_t;
 
 /** The main input device descriptor with driver, runtime data ('proc') and some additional
  * information*/
 typedef struct _lv_indev_t {
     lv_indev_drv_t * driver;
-    lv_indev_proc_t proc;
+    _lv_indev_proc_t proc;
     struct _lv_obj_t * cursor;     /**< Cursor for LV_INPUT_TYPE_POINTER*/
     struct _lv_group_t * group;    /**< Keypad destination group*/
     const lv_point_t * btn_points; /**< Array points assigned to the button ()screen will be pressed
diff --git a/src/widgets/lv_arc.c b/src/widgets/lv_arc.c
index d775260fc..e0f2064f8 100644
--- a/src/widgets/lv_arc.c
+++ b/src/widgets/lv_arc.c
@@ -523,7 +523,7 @@ static void lv_arc_event(const lv_obj_class_t * class_p, lv_event_t * e)
 
     lv_event_code_t code = lv_event_get_code(e);
     lv_obj_t * obj = lv_event_get_target(e);
-    lv_arc_t * arc = (lv_arc_t *)e->target;
+    lv_arc_t * arc = (lv_arc_t *)lv_event_get_target(e);
     if(code == LV_EVENT_PRESSING) {
         lv_indev_t * indev = lv_indev_get_act();
         if(indev == NULL) return;