private async void ImportFont(object sender, RoutedEventArgs e) { FileOpenPicker picker = new FileOpenPicker { ViewMode = PickerViewMode.Thumbnail, SuggestedStartLocation = PickerLocationId.DocumentsLibrary }; picker.FileTypeFilter.Add(".h"); StorageFile file = await picker.PickSingleFileAsync(); if (file != null) { this.Items.Clear(); CodeImport fontFile = new CodeImport(file); this.CurrentFile = await fontFile.Import(); this.CreateGrid(this.CurrentFile); this.Items.AddRange(this.CurrentFile.Items); this.FontName = file.Name; this.StorageFile = null; this.RaisePropertyChanged(nameof(this.Items)); } }