Flex Tree ,change the dataProvider but keep selectin and open items if possible

gistfile1.as

	public override function set dataProvider(value:Object):void
	{
	if(this.dataProvider==null)
		super.dataProvider=value;
	else{
	//want to keep the opened categories
		var fcarr:ArrayCollection=value as ArrayCollection;
		var openItems:Array=this.openItems as Array;
		var itemToOpen:Array=[];
		for each (var it:FeedCategory in openItems) {
			for each (var fc:FeedCategory in fcarr) 
			{
				if(it.title==fc.title)
				itemToOpen.push(fc);
			}
		}
		super.dataProvider=value;
		this.openItems=itemToOpen;
		}
	}