开始时隐藏主表单

Question

我想以隐藏模式启动应用程序，并在5秒钟后显示表单。为什么这段代码没有隐藏主窗口？

public MainWindow() : base(Gtk.WindowType.Toplevel)
{
    Build();

    this.Decorated = false;
    this.Modal = true;
    this.KeepAbove = true;

    Hide();

    GLib.Timeout.Add(5000, new GLib.TimeoutHandler(ShowForm));
}

bool ShowForm()
{
    this.ShowAll();
    label1.Text = DateTime.Now.ToString();
    return true;
}