public static ConfigurationManager GetInstance()
 {
     if (_instance == null)
     {
         return _instance = new ConfigurationManager();
     }
     return _instance;
 }
        private PreferencesForm()
        {
            InitializeComponent();

            _configManager = Configuration.ConfigurationManager.GetInstance();

            combobox_server_prefix.Items.Add("http://");
            combobox_server_prefix.Items.Add("https://");

            version_lbl.Text = string.Format("Version : {0}", System.Reflection.Assembly.GetExecutingAssembly().GetName().Version.ToString().Substring(0, 5));
        }