WPF彈出新窗口時判斷同標題的窗口是否存在

這是在做一個聊天軟件的時候遇到的問題：與多個人聊天需要彈出多個窗口，但是與同一個聊天的窗口只能是一個

我將聊天窗口的Name定義成ChatWindow，另外在打開聊天窗口時，根據聊天對象設置聊天窗口的Title

另外定義了一個 i  這個i我覺得很好用  

/// <summary>
        /// 雙擊人員名單列表項
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        void lstChatters_MouseDoubleClick(object sender, MouseButtonEventArgs e)
        {
            Person person = lstChatters.SelectedItem as Person;
            string title = "Chat with " + person.Name;
            int i = 0;
            foreach (Window win in Application.Current.Windows)//獲取當前應用程序實例化窗口
            {
                string type = win.GetType().ToString();
                if (type == "Hayu2012.ChatForm")
                {
                    if (String.Compare(win.Name, "ChatWindow") == 0 && String.Compare(win.Title, title) == 0)
                    {
                        i++;
                        win.Activate();
                        return;
                    }
                }
            }
            if (i == 0)
            {
                ChatForm cf = new ChatForm();
                cf.CurrentPerson = currPerson;
                cf.OtherPerson = lstChatters.SelectedItem as Person;
                cf.Title = title;
                cf.Show();
                return;
            }
        }