BaconographyWP8.View.ComposeMessagePageView.UpdateMenuItems C# (CSharp) Method

        private void UpdateMenuItems()
        {
            if (_appBarButtons == null || ApplicationBar.Buttons.Count == 0)
                BuildAppBar();

            var vm = this.DataContext as MessagesViewModel;
            if (vm != null)
                _appBarButtons[0].IsEnabled = vm.Compose.CanSend;
        }