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

这个是在bindable经常会碰到的警告,虽然是警告.但也要弄清楚.

 These warnings are there because if you have some code that modifies the individual fields of selectedItem, the binding mechanism will not be able to detect them. A better way to write this would be to create separate variables for the two values:

<?xml version="1.0"?>
<!-- Simple example to demonstrate the ComboBox control. --> <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml">

<mx:Script>
<![CDATA[

[Bindable]
public var cards: Array = [ {label:"Visa", data:1}, 
{label:"MasterCard", data:2}, {label:"American Express", data:3} ];

[Bindable]
public var selectedItemLabel:String = ""; 

[Bindable]
public var selectedItemData:String = ""; 

private function closeHandler(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="{cards}" width="150" 
close="closeHandler(event);"/>

<mx:VBox width="250">
<mx:Text width="200" color="blue" text="Select a type of credit card."/>
<mx:Label text="You selected: {selectedItemLabel}"/>
<mx:Label text="Data: {selectedItemData}"/>
</mx:VBox> 

</mx:Panel> 
</mx:Application>

转载：http://blog.csdn.net/songhuanren/article/details/1708545