private void SaveConfig()
{
string mediaFiles = string.Join(", ", MediaPlayList);
ConfigJSON["top"] = Top;
ConfigJSON["mediaFileList"] = mediaFiles;
ConfigJSON["left"] = Left;
ConfigJSON["width"] = Width;
ConfigJSON["height"] = Height;
ConfigJSON["lastMediaFileName"] = (LastMediaFileName == null)?"":LastMediaFileName;
ConfigJSON["lastMediaPosition"] = LastMediaPosition;
ConfigJSON["volume"] = Volume;
ConfigJSON["currentFileIndex"] = CurrentFileIndex;
File.WriteAllText(ConfigFileName, ConfigJSON.ToString());
}