UpdateDisplayList doesn't work for skin when called from hostcomponent

Question

I have skin class where I have overrided updateDisplayList like this:
override protected function updateDisplayList(unscaledWidth:Number, unscaledHeight:Number):void {
     switch (hostComponent.index) {
            case 0:
              part.right = 100;
              part.top = 100;
              break;
            case 1:
              part.right = 50;
              part.top = 50;
              break;
every time I update index in hostcomponent, I want to call the updateDisplayList in skin so I have done this:
public function set index(value:int):void {
        _index = value;
        invalidateDisplayList(); // doesn't work
        //updateDisplayList(); // doesn't work either      
... but this does not work. Can you please help me figure out what the problem is? Thanks.

Answer 1

Is index in the host component?  Maybe you need
    skin.invalidateDisplayList()