Arc : clickable area outside of the draw

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Hello
I don’t know if it’s a bug or if it’s desired, but it generate non desired behavior.

In my UI, on lvgl 8.3, I put an arc to control volume.
the arc is only on 120°, not full ring.

but when I click outside of this 120°, the even liked to the arc is called back and the volume is set to 100%, which is a litle too much…

it’s not a touch driver issue, it detect well I click outside of the arc.

Is it normal ???
how to prevent this ? I guess I’m not the only one who have this issue.

code :

// Volume
  lv_obj_t *volume_label = lv_label_create(lv_scr_act());
  lv_label_set_text(volume_label, "Value");

  /*Create Volume Arc*/
  volume_arc = lv_arc_create(lv_scr_act());
  lv_obj_set_size(volume_arc, 225, 225);
  // lv_arc_set_rotation(volume_arc, 135);
  lv_arc_set_rotation(volume_arc, 210);
  lv_obj_set_style_arc_width(volume_arc, 5, LV_PART_MAIN); // Changes background arc width
  lv_obj_set_style_arc_width(volume_arc, 6, LV_PART_INDICATOR); // Changes set part width 
  // lv_arc_set_bg_angles(volume_arc, 0, 270);
  lv_arc_set_bg_angles(volume_arc, 0, 120);
  lv_arc_set_value(volume_arc, 10);
  lv_obj_remove_style(volume_arc, NULL, LV_PART_KNOB);   /*Be sure the knob is not displayed*/
  lv_obj_center(volume_arc);
  lv_obj_add_event_cb(volume_arc, value_changed_event_cb, LV_EVENT_VALUE_CHANGED, volume_label);

and

static void value_changed_event_cb(lv_event_t * e)
{
    lv_obj_t * arc = lv_event_get_target(e);
    lv_obj_t * label = (lv_obj_t *)lv_event_get_user_data(e);

    lv_label_set_text_fmt(label, "%d%%", lv_arc_get_value(arc));
}

thanks in advance for your help.