How can I add a scroll bar for XML file in adobe flex

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Flex

Adobe

I am having an icon called 'Tools' in xml file.When the userclicks on the icon he/she will get the list of layers.

How can i add a scroll bar for the list.The layers doesnt have a design page so i have to add the list from xml page itself.

Belowcode shows the list

What I have tried:

<widgetgroup label="Tools" icon="assets/images/i_widget.png" layout="horizontal">
	
			
				
				<widget label="BQ Marketing Co. Filter" icon="assets/images/i_search.png" config="widgets/BQProfileFilter/BQProfileFilter_Prod.xml" url="widgets/BQProfileFilter/BQProfileFilter.swf">
				
				
				<!--Saikrishna-->
<widget label="CSC Filter" icon="assets/images/i_search.png" config="widgets/CSCFilter/CSCFilter_Prod.xml" url="widgets/CSCFilter/CSCFilter.swf">
<!--Till here-->

			<widget label="Dist. Center Filter" icon="assets/images/i_search.png" config="widgets/DistributionFilter/DistributionFilter_Prod.xml" url="widgets/DistributionFilter/DistributionFilter.swf">