public DownloadDialogViewModel(IUnityContainer container) : base(container) { var downloadDirectory = Container.Resolve <IConfigureFile>().GetValue <FileLocator>(ConfigureKeys.DownloadDirectory); DefaultFolders = new ObservableCollection <FileLocator>(SystemFolder.GetAvailableFolders()); DownloadFolder = string.IsNullOrEmpty(downloadDirectory) ? DefaultFolders.FirstOrDefault() : downloadDirectory; OpenFolderDialogCommand = new RelayCommand(OpenFolderDialogCommandExecute); DownloadCommand = new RelayCommand( () => { if (DialogHost.CloseDialogCommand.CanExecute(true, null)) { DialogHost.CloseDialogCommand.Execute(true, null); } }, () => !string.IsNullOrEmpty(DownloadFolder)); }