dropdownStyleName样式和 verticalScrollBarStyleName 样式.的学习
示例： 代码：

<?xml version="1.0" encoding="utf-8"?><!--http://blog.flexexamples.com/2007/12/29/styling-a-flex-3-combobox-controls-vertical-scroll-bars/--><mx:Applicationxmlns:mx="http://www.adobe.com/2006/mxml"layout="vertical"verticalAlign="top"backgroundColor="white"><mx:Style>.myCustomComboBox {
            dropdownStyleName: myCustomDropdown;
        }

.myCustomDropdown {
            fontWeight: normal;
            verticalScrollBarStyleName: myCustomVertScroll;
        }

.myCustomVertScroll {
            trackColors: white, white;
            upArrowSkin: Embed("bullet_delete.png");
            downArrowSkin: Embed("bullet_add.png");
        }</mx:Style><mx:Arrayid="arr"><mx:Objectlabel="One"/><mx:Objectlabel="Two"/><mx:Objectlabel="Three"/><mx:Objectlabel="Four"/><mx:Objectlabel="Five"/><mx:Objectlabel="Six"/><mx:Objectlabel="Seven"/></mx:Array><mx:Form><mx:FormItemlabel="default:"><mx:ComboBoxid="comboBox1"dataProvider="{arr}"/></mx:FormItem><mx:FormItemlabel="skinned:"><mx:ComboBoxid="comboBox2"dataProvider="{arr}"styleName="myCustomComboBox"/></mx:FormItem></mx:Form></mx:Application>