去掉StartupUri="Login.xaml"

去掉StartupUri="Login.xaml"

public partial class App : Application
    { 
        protected override void OnStartup(StartupEventArgs e)
        {
            try
            {
                base.OnStartup(e);
                Login mainWin = new Login();
                mainWin.Show(); 
            }
            catch(Exception ex)
            {
                MessageBox.Show(App.Current.MainWindow as Login,ex.Message,"系统错误",MessageBoxButton.OK,MessageBoxImage.Error);
                App.Current.Shutdown();
            }
        }
        
    }