SparkDataContainer Scroller not scrolling to bottom of container

Question

I am using a scroller component within a custom skin for a SkinnableDataContainer. I am running into an issue in that the thumbbar of the scroller stops at about the 50% point, however this is actually the end of the scrollable area. In actuality, the thumbbar should be at the bottom of the scroll track. Here's the code for the scroller:
<s:SparkSkin xmlns:fx="http://ns.adobe.com/mxml/2009"
                xmlns:s="library://ns.adobe.com/flex/spark"
                xmlns:mx="library://ns.adobe.com/flex/halo" bottom="150"  >
     <!-- Properties of the parent ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
     <s:states>
          <s:State name="normal" />
          <s:State name="disabled" />
     </s:states>    
     <!-- Metadata ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->    
     <fx:Metadata>
          [HostComponent("spark.components.SkinnableDataContainer")]
     </fx:Metadata>    
     <!-- UI components ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
     <s:Rect left="0" right="0"
               bottom="0" top="0"
               radiusX="4" radiusY="4"   >
          <s:fill>
               <s:SolidColor id="fillColor" color="0xEFEFEF"/>
          </s:fill>
     </s:Rect>    
     <s:Group width="905" height="395" id="mainGroup">
          <s:Scroller left="10" right="10" top="4" bottom="10" >
                    <s:DataGroup id="dataGroup" />                   
          </s:Scroller>
          <s:Rect left="0" right="0" top="0" bottom="0">
               <s:stroke>
                    <s:SolidColorStroke weight="1" color="0xD8D8D8"/>
               </s:stroke>
          </s:Rect>
     </s:Group>
</s:SparkSkin>

Answer 1

Can you please post a small sample application that demonstrates this?  I was unable to reproduce it using the skin you posted above with this small sample application:
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
               xmlns:s="library://ns.adobe.com/flex/spark">
    <fx:Script>
        <![CDATA[
            import mx.collections.ArrayList;
            private function getArray(n:int = 100):ArrayList {
                var arr:Array = new Array(n);
                for (var i:int = 0; i < n; i++){
                    arr[i] = i;   
                return new ArrayList(arr);
        ]]>
    </fx:Script>
    <s:SkinnableDataContainer itemRenderer="spark.skins.spark.DefaultItemRenderer"
                              dataProvider="{getArray()}"
                              skinClass="CustomDataContainerSkin">
        <s:layout>
            <s:VerticalLayout />
        </s:layout>
    </s:SkinnableDataContainer>
</s:Application>