Removing the thumb button on a Spark VScrollBar control in Flex 4

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2009/02/26/removing-the-thumb-button-on-a-fxvscrollbar-control-in-flex-gumbo/ -->
<s:Application name="Spark_VScrollBar_skinClass_thumb_test"
        xmlns:fx="http://ns.adobe.com/mxml/2009" 
        xmlns:s="library://ns.adobe.com/flex/spark" 
        xmlns:mx="library://ns.adobe.com/flex/halo">
 
    <fx:Style>
        @namespace s "library://ns.adobe.com/flex/spark";
        @namespace mx "library://ns.adobe.com/flex/halo";
 
        s|TextArea s|VScrollBar {
            skinClass: ClassReference("skins.CustomVScrollBarSkin");
        }
    </fx:Style>
 
    <fx:Script>
        <![CDATA[
            import spark.utils.TextFlowUtil;
        ]]>
    </fx:Script>
 
    <fx:Declarations>
        <fx:String id="lorem" source="lorem.html" />
    </fx:Declarations>
 
    <s:VGroup horizontalCenter="0" verticalCenter="0">
        <s:TextArea id="textArea"
                textFlow="{TextFlowUtil.importFromString(lorem)}"
                verticalScrollPolicy="on"
                editable="false" />
 
        <s:VScrollBar id="vsb"
                minimum="0"
                maximum="1000" />
    </s:VGroup>
 
</s:Application>

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2009/02/26/removing-the-thumb-button-on-a-fxvscrollbar-control-in-flex-gumbo/ -->
<s:SparkSkin name="CustomVScrollBarSkin"
        xmlns:fx="http://ns.adobe.com/mxml/2009"
        xmlns:s="library://ns.adobe.com/flex/spark"
        minWidth="15" minHeight="35"
        alpha.disabled="0.5">
    <s:states>
        <s:State name="normal" />
        <s:State name="disabled" />
    </s:states>
 
    <fx:Metadata>
        <![CDATA[ 
        [HostComponent("spark.components.VScrollBar")]
        ]]>
    </fx:Metadata> 
 
    <fx:Script>
        /* Define the skin elements that should not be colorized. 
        For scroll bar, the skin itself is colorized but the individual parts are not. */
        static private const exclusions:Array = ["track", "decrementButton", "incrementButton"];
 
        override public function get colorizeExclusions():Array {return exclusions;}
    </fx:Script>
 
    <!--- Defines the skin class for the VScrollBarSkin's track. The default skin class is VScrollBarTrackSkin. -->
    <s:Button id="track" top="16" bottom="15" height="54"
              focusEnabled="false"
              skinClass="spark.skins.spark.VScrollBarTrackSkin" />
 
    <!--- Defines the skin class for the up button of the VScrollBarSkin. The default skin class is ScrollBarUpButtonSkin. -->
    <s:Button id="decrementButton" top="0"
              focusEnabled="false"
              skinClass="spark.skins.spark.ScrollBarUpButtonSkin" />
 
    <!--- Defines the skin class for the down button of the VScrollBarSkin. The default skin class is ScrollBarDownButtonSkin. -->
    <s:Button id="incrementButton" bottom="0"
              focusEnabled="false"
              skinClass="spark.skins.spark.ScrollBarDownButtonSkin" />
 
</s:SparkSkin>