Flex :: WindowShade Component Opened State - How To Maintain

I have flexlib WindowShade component in repeater in my Flex + AIR application.
<mx:XML id="mainMenuXML"><items>
<item value="abc" />
<item value="xyz" />
<item value="lmn" />
</items></mx:XML>

Now in button1 click handler I am appending child in XML(mainMenuXML) resulting adding one more windowshade instance. But the problem is it opens all the windowshade instances. I need to maintain the opened states after adding a new windowshade instance.

For example:
Initially I get 3 windoshades with labels: abc, xyz, lmn all opened.
Now I close the xyz windowshade instance(by clicking on the header)
Now I click on button which appends child in mainMenuXML and also add a windowshade instance with some label "pqr". But now I see all the windowshade instances opened.
But it should be like abc, lmn, pqr should be opened & xyz closed(property opened="false").

How to maintain the opened true/false state of windowshade instances. I tried to add a property in dataprovider Bindable to opened property of windhowshade but didn't worked for me.