private Paragraph GetParagraphOfBeobachtung(Beobachtung b)
 {
     foreach (var i in Document.Blocks)
     {
         if (i is Paragraph && i.Tag is int && ((int) i.Tag) == b.BeobachtungId)
             return (Paragraph) i;
     }
     return null;
 }
        public void AddCurrentComment(bool clear = true)
        {
            // Save current comment
            foreach (Schueler s in SelectedSchülerList)
            {
                Beobachtung b = new Beobachtung()
                {
                    Datum = BeoDatum,
                    Fach = (SelectedFach == null || SelectedFach.FachId == -1000) ? null : SelectedFach,
                    Text = BeoText,
                    SchuljahrId =  Settings.ActiveSchuljahr.Startjahr,
                    Schueler = s
                };
                UnitOfWork.Beobachtungen.Add(b);
            }

            UnitOfWork.Save();
            UpdateHistory();

            if (clear)
                BeoText = "";
        }