/// <summary>
        /// Отображает или убирает кнопку "Вниз"
        /// </summary>
        /// <param name="isVisible"></param>
        public async void ShowButtonToBottomAsync(bool isVisible)
        {
            IsFocus = false;
            if (_cache.IndexLevel == 0 && CountNewMessages == 0 && !_haveNewMessage)
            {
                IsVisibleButtonToBottom = isVisible;
                await Task.Run(() => _serverWorker.GetUpdate(!IsVisibleButtonToBottom));

                if (IsVisibleButtonToBottom)
                {
                    GetFlickerAsync();
                }
                else
                {
                    CountNewMessages = 0;
                }
                _countClickButtonToBottom = 0;
                IsFocus = true;
            }
            else if (_cache.IndexLevel > 0 && _isGoToBottom == false)
            {
                _isGoToBottom = true;
                Application.Current.Dispatcher.Invoke(LoadFromCache, DispatcherPriority.Background);
                _countClickButtonToBottom = 0;
                IsFocus = true;
            }
            else if (_cache.IndexLevel > 0)
            {
                _isGoToBottom = false;
                IsFocus       = true;
            }
            else if (CountNewMessages > 0 && _isGoToBottom == false)
            {
                if (CountNewMessages > 100)
                {
                    await Task.Run(() => _serverWorker.GetMessages(Messages[Messages.Count - 1].Id, "New messages"));
                }
                else
                {
                    CountNewMessages = 0;
                    var mapper = new MapperConfiguration(cfg => cfg.CreateMap <Message, ChatMessageDTO>()).CreateMapper();
                    await Task.Run(() => _serverWorker.GetMessages(mapper.Map <Message, ChatMessageDTO>(MessagesContainer.GetMessage())));
                }
                _countClickButtonToBottom = 0;
            }
            else
            {
                _isGoToBottom = false;
            }
        }