c# winform 显示一个 tip

public void showTip(string text, int duration = 2000)
{
    var form = new Form { Size = new Size(1, 1), StartPosition = FormStartPosition.CenterScreen };
    var tooltip = new System.Windows.Forms.ToolTip();
    form.Opacity = 0;
    form.TopMost = true;
    form.Show();
    tooltip.Show(text, form, new Point(0, 0));
    Task.Factory.StartNew(() =>
    {
        System.Threading.Thread.Sleep(duration);
        form.Invoke(new MethodInvoker(delegate ()
        {
            form.Close();
        }));
    });
}