     }
 
     /**
-     *  This utility method calculates an appropriate size for
-     *  the thumb, given the current range, pageSize, and
+     *  Calculate the size for
+     *  the thumb from the current range, pageSize, and
      *  trackSize settings.
      */
     override protected function calculateThumbSize():Number

    [SkinPart(required="false")]
    
    /**
     *  <code>decrementButton</code> is an optional SkinPart that defines a button 
     *  that, when pressed, will step the scrollbar "up", which is equivalent 
     *  to a decreasing step in the <code>value</code> property.
     */
    public var decrementButton:FxButton;
    
    [SkinPart(required="false")]
    
    /**
     *  <code>incrementButton</code> is an optional SkinPart that defines a button 
     *  that, when pressed, will step the scrollbar "down", which is equivalent
     *  to a increasing step in the <code>value</code> property.
     */
    public var incrementButton:FxButton;
    

import mx.core.IViewport;

/**
 *  The FxScrollBar class helps to position
 *  the portion of data that is displayed when there is too much data
 *  to fit in a display area. 
 *  The FxScrollBar class displays a pair of scrollbars and a viewport. 
 *  A viewport is a UIComponent that implements IViewport, such as Group.
 *  
 *  <p>This control extends the FxTrackBase class and
 *  is the base class for the FxHScrollBar and FxVScrollBar
 *  controls.</p> 
 * 
 *  <p>A scroll bar consists of a track, a variable-size scroll thumb, and 
 *  two optional arrow buttons. The FxScrollBar class uses four parameters 
 *  to calculate its display state:</p>
 *
 *  <ul>
