 package mx.layout
 {
 
+import flash.events.Event;
 import flash.geom.Rectangle;
 import flash.ui.Keyboard;
 
 import mx.components.baseClasses.GroupBase;
+import mx.core.ScrollUnit;
+import mx.layout.ILayoutItem;
 import mx.utils.OnDemandEventDispatcher;
 
-    
+
 public class LayoutBase extends OnDemandEventDispatcher
 {
     //--------------------------------------------------------------------------

    /**
     *  @copy flex.intf.IViewport#horizontalScrollPositionDelta
     */
    public function horizontalScrollPositionDelta(unit:uint):Number
    {
        var g:GroupBase = target;
        if (!g)

    }
    
    /**
     *  If clipContent is true, sets the origin of the scrollRect to 
     *  verticalScrollPosition,horizontalScrollPosition and its width
     *  width,height to w,h (the target's unscaled width,height).
     * 
     *  If clipContent is false, sets the scrollRect to null.
     *  
     *  @param w The target's unscaled width.
     *  @param h The target's unscaled height.
     * 
     *  @see target
     *  @see flash.display.DisplayObject#scrollRect
     *  @see updateDisplayList
     */ 
    public function updateScrollRect(w:Number, h:Number):void
    {
        var g:GroupBase = target;
        if (!g)
            return;
            
        if (clipContent)
        {
            var hsp:Number = horizontalScrollPosition;
            var vsp:Number = verticalScrollPosition;
            g.scrollRect = new Rectangle(hsp, vsp, w, h);
        }
        else
            g.scrollRect = null;
    } 
    
