javascript编写了一段代码，无法实现esc键弹出与关闭窗口，请高手帮忙解决一下，代码如下
#pragma strict
static var WindowSwitch :boolean = false
private var windowRect = Rect (240, 200, 240, 200);
function Update () {
if(Input.GetKeyDown(KeyCode.Escape)){
WindowSwitch = !WindowSwitch;
}
function OnGUI () { if(WindowSwitch == true){
windowRect = GUI.Window (0,windowRect, WindowContain, "测试窗口");
}
}
function WindowContain (windowID : int){
if (GUI.Button (Rect (70,70,100,20), "关闭音乐")) {gameObject.Find("Terrain").GetComponent(AudioSource).enabled=false;}
if (GUI.Button (Rect (70,100,100,20), "播放音乐")) {gameObject.Find("Terrain").GetComponent(AudioSource).enabled=true;}
if (GUI.Button (Rect (70,130,100,20), "关闭窗口")) { WindowSwitch = false;}
if (GUI.Button (Rect (70,160,100,20), "退出游戏")) { Application.Quit();}
GUI.DragWindow(new Rect(0,0,1000,1000));
}
