public void RemoveAttachFile(string id)
        {
            var item = AttachFileList.Single(f => f.Id.Equals(id));

            _fileRemoveList.Add(item.Id);
            AttachFileList.Remove(item);
        }
        async void ShowUnusedImage(CancellationTokenSource cts)
        {
            var unusedImageAttachList = await SendService.LoadUnusedAttachFilesAsync(cts);

            if (unusedImageAttachList != null && unusedImageAttachList.Count > 0)
            {
                if (AttachFileList == null)
                {
                    AttachFileList = new ObservableCollection <AttachFileItemModel>();
                }

                var list = AttachFileList.ToList();
                foreach (var item in unusedImageAttachList)
                {
                    if (list.Count(i => i.Id.Equals(item.Id)) == 0)
                    {
                        AttachFileList.Add(item);
                    }
                }
            }
        }
        public void InsertAttachFile(string id)
        {
            var item = AttachFileList.Single(f => f.Id.Equals(id));

            _insertFileCodeIntoContentTextBox($"[attachimg]{item.Id}[/attachimg]\r\n");
        }