The other day i was trying to get a list control to have multiple items set on startup however how to do this was not immediately obvious and after searching the web it seems quite a few other were having the same issue.

Eventually I found the answer on Bruce Phillips blog, thanks a bunch Bruce!

It basically boils down to doing this.

Have a creation complete function on the application which will set the lists selected indices to an array... voila.

Example...

<?xml version="1.0" encoding="utf-8"?>
 <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute"
 creationComplete="initApp();" width="243" height="429">

   <mx:Script>
     <![CDATA[
       import mx.collections.ArrayCollection;

        [Bindable]
       public var aDemo:ArrayCollection = new ArrayCollection(
         [ {label:"me", data:"me"},
           {label:"you", data:"you"}, 
           {label:"boo", data:"a dog named boo"} 
 	]);

        private function initApp():void {
         //the array of selected indicies, this can be derived however you want.
         var aTmp:Array = new Array(0,2);

          // set the selectedindicies... and thats it
         lstDemo.selectedIndices = aTmp;
       }
   ]]>
   </mx:Script>

    <mx:List id="lstDemo" allowMultipleSelection="true" dataProvider="{aDemo}" ></mx:List>

  </mx:Application>