item renderer in List

[nikos101]

I'm trying to create a list that contains an item renderer with a label. I know to change its background color depending on a number eg

                              
       override protected function updateDisplayList(unscaledWidth:Number, unscaledHeight:Number):void
                             {
                                 
                                 super.updateDisplayList(unscaledWidth, unscaledHeight);
                            if (oldData)
                             {
                                 var g:Graphics=ask.graphics;
                                 // g = graphics;
                                 g.clear();
                                 if (oldData <  data.Ask)
                                 {
                                     //unmatched
                                     g.beginFill(0x00ff00);
                                     g.drawRect(ask.x, 0, ask.width, unscaledHeight);
                                     g.endFill();
                                 }
                                 else if (oldData >  data.Ask)
                                 {
                                     //matched
                                     g.beginFill(0xff0000);
                                     g.drawRect(ask.x, 0, ask.width, unscaledHeight);
                                     g.endFill();
                                 }else{
                                 //     g.beginFill(0xffffff);
                                    // g.drawRect(ask.x, 0, ask.width, unscaledHeight);
                                //     g.endFill();
                                 }
                             }

But what I don't know what to do is remember the previous number shown in the label and change the background colour