How to validate a <mx:List component> ?

Question

How can I validate if atleast one item has been selected from a list, such that the selectedIndices is set to NULL at the init() of application?

Answer 1

Following code can be of help to someone who want to validate a list like I wanted:

<mx:NumberValidator 
         id               ="myListValidator"
         trigger          ="{myButton}" 
         triggerEvent     ="click"  
         minValue         ="0"
         lowerThanMinError="Should I write an application to you for selecting atleast one of the option X-(" 
         source           ="{myList}" 
         property         ="selectedIndex"
 />