DispatcherTimer不与keyDownEvent回调打勾

Question

当存在按键按下事件回调时，分派器计时器不会计时。 在实际程序中，输入被传递到另一个线程进行处理和 返回到UI线程进行显示。

每个用户输入我都需要一个持久弹出窗口

namespace TextBoxTest
{
    public partial class MainWindow : Window
    {
        static public StreamWriter tw = new StreamWriter("T_file.txt");
        static private bool flg;
        static private string ss;
        public MainWindow()
        {
            InitializeComponent();

            DispatcherTimer timer = new DispatcherTimer();
            timer.Tick += TimerTick;
            timer.Interval = TimeSpan.FromSeconds(1);
            timer.Start();
            flg = false;

            tw.WriteLine("window initial");
            tw.Flush();
        }

        private void keyDownEvent (object sender, KeyEventArgs e)
        {
            if (e.Key == Key.Return)
            {
                tw.WriteLine("keydown -- return");
                tw.Flush();
                var textbox = sender as TextBox;
                tw.WriteLine(textbox.Text);
                ss = textbox.Text;
                tw.Flush();
                textbox.Text = "";
                flg = true;
            }
        }
        public void TimerTick(object sender, EventArgs e)
        {
            tw.WriteLine("timer tick entry");
            tw.Flush();

            if (flg == false) return;
            Window wa = new Window();
            wa.Height = 100;
            wa.Width = 200;
            wa.Title = "CCC";
            wa.Content = ss;
            wa.Show();

            flg = false;

            tw.WriteLine("timer tick exit");
            tw.Flush();
        }
    }
}

Timer tick未输入。