public async void Edit(object sender)
        {
            ConnectionViewModel source = (ConnectionViewModel)sender;
            NewConnectionPage   nc     = new NewConnectionPage(source, false);

            Update();
            await Navigation.PushAsync(nc);
        }
        private async void Create()
        {
            Connection connection = new Connection();

            Global.Parameters.Connections.Add(connection);
            ConnectionViewModel cvm = new ConnectionViewModel(Navigation, connection);

            ConnectionViewModels.Add(cvm);
            NewConnectionPage nc = new NewConnectionPage(cvm, true);
            await Navigation.PushAsync(nc);
        }