private void NewSingleChat(string remoteIP, string NickName, string msg)
        {
            SingleChatWindow window = new SingleChatWindow
            {
                RemoteIP = remoteIP
            };

            window.SetNickName(NickName);
            instance.singleWindows.Add(window);
            window.Show();
            if (!msg.Equals(string.Empty))
            {
                window.NewMessage(msg);
            }
        }
        private void ListBoxItem_MouseDoubleClick(object sender, RoutedEventArgs e)
        {
            User             user   = (User)Lb_Member.SelectedItem;
            SingleChatWindow window = instance.singleWindows.Find(x => x.RemoteIP.Equals(user.IP));

            if (window != null)
            {
                window.Focus();
                return;
            }
            else
            {
                window = new SingleChatWindow()
                {
                    RemoteIP = user.IP
                };
                window.SetNickName(user.NickName);
                instance.singleWindows.Add(window);
                window.Show();
            }
        }