private async void FillRichTextBox(string text)
 {
     var start = 0;
     var regex = new Regex("\\$\\[img:[0-9]+\\]\\$");
     var paragraph = new Paragraph();
     foreach (Match match in regex.Matches(text))
     {
         var imageId = Int32.Parse(Regex.Match(match.Value, @"[0-9]+").Value);
         System.Diagnostics.Debug.WriteLine(imageId);
         paragraph.AddText(start, match.Index, text);
         await paragraph.ReplaceLabelWithImage(imageId);
         start = match.Index + match.Length;
     }
     paragraph.AddText(start, text.Length, text);
     //App.ViewModel.Blocks.Add(paragraph);
     RichTextBox.Blocks.Add(paragraph);
 }