private async void DeleteDownloads_OnClick(object sender, RoutedEventArgs e)
        {
            deleteDownloads.IsEnabled = false;

            var ctx = new RisDbContext();
            await ctx.DeleteDownloads();

            MessengerHelper.Notify(MessengerHelper.DownloadsDeleted);
        }
        private async void DeleteHistory_OnClick(object sender, RoutedEventArgs e)
        {
            deleteHistory.IsEnabled = false;

            var ctx = new RisDbContext();
            await ctx.DeleteSearchHistory();

            MessengerHelper.Notify(MessengerHelper.SearchHistoryDeleted);
        }