I was having this same issue. I ended up subclassing the mx.controls.List class and overriding the clearHighlight function. As far as I can tell, the lastHighlightItemIndices variable is only ever read in that function. So doing something like the following fixed this issue:
import mx.core.mx_internal;
use namespace mx_internal;
public class List extends mx.controls.List
{
public function List()
{
super();
}
override mx_internal function clearHighlight( item:IListItemRenderer ):void
{
var uid:String = itemToUID( item.data );
drawItem( UIDToItemRenderer( uid ), isItemSelected( item.data ), false, uid == caretUID );
var pt:Point = itemRendererToIndices( item );
if( pt )
{
var listEvent:ListEvent = new ListEvent( ListEvent.ITEM_ROLL_OUT );
listEvent.columnIndex = item.x;
listEvent.rowIndex = item.y;
listEvent.itemRenderer = item;
dispatchEvent( listEvent );
}
}
}
Then just use this List class instead of the Adobe one and you'll have the behavior you expect. I tested this against Flex SDK 3.2 and it works.
<mx:Canvas xmlns:mx="http://www.adobe.com/2006/mxml" xmlns:controls="com.example.controls.*">
[ other code ... ]
<controls:List itemRollOver="onItemRollOver( event )" itemRollOut="onItemRollOut( event )" />
</mx:Canvas>
Thanks to Gino Basso for the idea in the post above. Hope that helps.