warning: unable to bind to property '' on class '' (class is not an IEventDispatcher)

早上在编程的时候出现 warning: unable to bind to property '' on class 'Object' (class is not an IEventDispatcher) 这种警告！
这些警告，因为如果你有一些代码，修改了个别领域的selectedItem ，有约束力的机制，将无法探测到它们。一种更好的方式来写这将是建立独立的两个变量的值
比如：
<?xml version="1.0"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml">
<mx:Script>
<![CDATA[
[Bindable]
public var arr: Array = [ {label:"a1", data:1}, {label:"a2", data:2}, {label:"a3", data:3} ];
[Bindable]
public var selectedItemLabel:String = "";
[Bindable]
public var selectedItemData:String = "";
private function Handler(event:Event):void
{
selectedItemLabel=ComboBox(event.target).selectedItem.label;
selectedItemData=ComboBox(event.target).selectedItem.data;
}
]]>
</mx:Script>
<mx:Panel title="ComboBox Control Example"
height="75%" width="75%" layout="horizontal"
paddingTop="10" paddingBottom="10" paddingLeft="10" paddingRight="10">
<mx:ComboBox dataProvider="{arr}" width="150"
close="Handler(event);"/>
<mx:VBox width="250">
<mx:Text width="200" color="blue" text="selectedItem example!"/>
<mx:Label text="the Selected: {selectedItemLabel}"/>
<mx:Label text="the Data: {selectedItemData}"/>
</mx:VBox>
</mx:Panel>
</mx:Application>