private void RandomDownloadFolder_Click(object sender, RoutedEventArgs e)
{
Config cfg = new Config();
JObject config = cfg.Load();
config[download_folder] = Random2.RandomString(int.Parse(new InputBox("랜덤 길이 지정", "설정", "").ShowDialog()));
cfg.Save(config);
FolderName.Content = config.StringValue(download_folder);
}