<?xml version="1.0"?>
  <mx:ToggleButtonBar xmlns:mx="http://www.adobe.com/2006/mxml" initialize="registerManager()" itemClick="buttonClicked()" implements="mx.managers.IHistoryManagerClient">
    <mx:Script>
      <![CDATA[
      import mx.managers.HistoryManager;
                  // method to register with HistoryManager
      private function registerManager():void {
        HistoryManager.register(this);
      }
                  // called when button is clicked
      private function buttonClicked():void {
        HistoryManager.save();
      }
      // Save the  selectedIndex.  ** Required Method **
      public function saveState():Object {
        return { selectedIndex: selectedIndex };
      }
      // Load the selectedIndex  ** Required Method **
      public function loadState(state:Object):void {
        var newIndex:int = state ? int(state.selectedIndex) : -1;
        if (newIndex != selectedIndex)
        selectedIndex = newIndex;
      }
      ]]>
    </mx:Script>
  </mx:ToggleButtonBar>