AS3 navigateToURL導致ExternalInterface 執行失敗問題_Flash as3

我們先看下面代碼：

複製代碼 代碼如下:

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute">
<mx:Script>
<!--[CDATA[
import flash.external.ExternalInterface;
private function init1():void
{
var url:String = "javascript:alert('執行navigateToURL');";
var request:URLRequest = new URLRequest(url);
navigateToURL(request,"_self");
}
private function init2():void
{
ExternalInterface.call("function function1(){alert('執行ExternalInterface');}");
}
private function clickfun():void
{
ExternalInterface.call("function function2(){window.document.title = '更改後的標題';}");
}
]]-->
</mx:Script>
<mx:Button x="150" y="92" label="1" click="init1()"/>
<mx:Button x="544" y="92" label="2" click="init2()"/>
<mx:Button x="404" y="315" label="更改標題" click="clickfun()"/>
</mx:Application>
<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute">

<mx:Script>
<!--[CDATA[
import flash.external.ExternalInterface;

private function init1():void
{
var url:String = "javascript:alert('執行navigateToURL');";
var request:URLRequest = new URLRequest(url);
navigateToURL(request,"_self");
}
private function init2():void
{
ExternalInterface.call("function function1(){alert('執行ExternalInterface');}");
}

private function clickfun():void
{
ExternalInterface.call("function function2(){window.document.title = '更改後的標題';}");
}

]]-->
</mx:Script>
<mx:Button x="150" y="92" label="1" click="init1()"/>
<mx:Button x="544" y="92" label="2" click="init2()"/>
<mx:Button x="404" y="315" label="更改標題" click="clickfun()"/>

</mx:Application>

函數init1和init2都是通過javascript彈出提示框，clickfun()為修改網頁標題。
3個函數單獨執行都是成功的，但當
1.先執行init1函數後再調用clickfun函數，會發現clickfun執行失敗。
2.先執行init2函數後再調用clickfun函數，會發現clickfun執行成功。
難道是navigateToURL會導致ExternalInterface 執行失敗？？請知道原因的朋友指導下。