     function set horizontalScrollPosition(value:Number):void;
      
      /**
-     *  The Y coordinate of the origin of the region this Group is
-     *  scrolled to.  
-     * 
-     *  If clipAndEnableScrolling is true, setting this property typically causes 
-     *  the <code>scrollRect</code> to be set to:
+     *  The y coordinate of the origin of the viewport in the component's coordinate system, 
+     *  where the default value is (0,0) corresponding to the upper-left corner of the component.
+     * 
+     *  If <code>clipAndEnableScrolling</code> is <code>true</code>, setting this property 
+     *  typically causes the viewport to be set to:
      *  <pre>
      *  new Rectangle(horizontalScrollPosition, verticalScrollPosition, width, height)
-     *  </pre>                 
+     *  </pre>
      * 
      *  Implementations of this property must be Bindable and
-     *  they must generate events of type "propertyChange".
+     *  must generate events of type <code>propertyChange</code>.
      *   
      *  @default 0
+     * 
      *  @see horizontalScrollPosition
      *  
      *  @langversion 3.0

    function get contentHeight():Number;

    /**
     *  The X coordinate of the origin of the region the target is
     *  scrolled to.  
     * 
     *  If clipAndEnableScrolling is true, setting this property typically causes 
     *  <code>scrollRect</code> to be set to:
     *  <pre>
     *  new Rectangle(horizontalScrollPosition, verticalScrollPosition, width, height)
     *  </pre>
     * 
     *  Implementations of this property must be Bindable and
     *  they must generate events of type "propertyChange".
     *   
     *  @default 0
     *  @see target
     *  @see verticalScrollPosition
     *  

    function getHorizontalScrollPositionDelta(scrollUnit:uint):Number;
    
    /**
     *  Returns the amount to add to the viewport's current 
     *  <code>verticalScrollPosition</code> to scroll by the requested scrolling unit.
     *
     *  @param scrollUnit The amount to scroll. 
     *  The value of unit must be one of the following spark.core.ScrollUnit
     *  constants: <code>UP</code>, <code>DOWN</code>, <code>PAGE_UP</code>, 
     *  <code>PAGE_DOWN</code>, <code>HOME</code>, or <code>END</code>.
     *  To scroll by a single row use <code>UP</code> or <code>DOWN</code>.
     *  To scroll to the first or last row, use <code>HOME</code> or <code>END</code>.
     *
     *  @return The number of pixels to add to <code>verticalScrollPosition</code>.
     * 
     *  @see ScrollUnit
     *  
