如何在scala swing中断窗口关闭机制

import scala.swing._
import scala.swing.event._

object Main extends SimpleSwingApplication {
  def top = new MainFrame {
    title = "Scala Swing 窗口关闭示例"
    contents = new BoxPanel(Orientation.Vertical) {
      contents += new Label("这是一个简单的 Scala Swing 应用程序")
    }
    size = new Dimension(300, 200)
    listenTo(this)
    reactions += {
      case WindowClosing(_) =>
        println("窗口关闭中...")
        System.exit(0)
    }
  }
}