private void DgTicket_MouseDoubleClick(object sender, MouseButtonEventArgs e)
        {
            try
            {
                mv.SelToEdt();
                TicketWindow td = new TicketWindow();

                // Databinding (manuell) aktualisiert

                /*td.TbId.GetBindingExpression(TextBox.TextProperty).UpdateTarget();
                 * td.TbBeschreibung.GetBindingExpression(TextBox.TextProperty).UpdateTarget();
                 * td.TbName.GetBindingExpression(TextBox.TextProperty).UpdateTarget();
                 * td.CmbStatus.GetBindingExpression(ComboBox.ItemsSourceProperty).UpdateTarget();
                 * td.CmbStatus.GetBindingExpression(ComboBox.SelectedItemProperty).UpdateTarget();
                 * td.DpErdat.GetBindingExpression(DatePicker.SelectedDateProperty).UpdateTarget();*/

                // Neues Window aufrufen
                td.ShowDialog();
                mv.Speichern();

                //funktioniert nicht
                //DgTicket.Items.Refresh();

                //Verzweiflungstat
                DgTicket.ItemsSource = null;
                DgTicket.ItemsSource = mv.LTickets;
            }catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }
        private void TicketNeu_Click_1(object sender, RoutedEventArgs e)
        {
            try
            {
                mv.NewTicket();
                TicketWindow td = new TicketWindow();

                td.ShowDialog();
                mv.Speichern();
                DgTicket.Items.Refresh();
            }catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }