checkbox: allow setting _getValue later

radio/src/thirdparty/libopenui/src/checkbox.cpp

@@ -46,7 +46,7 @@ CheckBox::CheckBox(Window* parent, const rect_t& rect,
   lv_obj_set_style_bg_color(lvobj, makeLvColor(COLOR_THEME_DISABLED), LV_PART_MAIN);
   lv_obj_set_style_bg_color(lvobj, makeLvColor(COLOR_THEME_DISABLED), LV_STATE_FOCUSED);
 
-  if (_getValue()) lv_obj_add_state(lvobj, LV_STATE_CHECKED);
+  if (_getValue && _getValue()) lv_obj_add_state(lvobj, LV_STATE_CHECKED);
 
   lv_obj_add_event_cb(lvobj, checkbox_event_handler,
                       LV_EVENT_VALUE_CHANGED, this);

radio/src/thirdparty/libopenui/src/checkbox.h

@@ -46,6 +46,11 @@ class CheckBox : public FormField
     _setValue = std::move(handler);
   }
 
+  void setGetValueHandler(std::function<uint8_t()> handler)
+  {
+    _getValue = std::move(handler);
+  }
+
  protected:
   std::string label;
   std::function<uint8_t()> _getValue;