 
 package spark.components
 {
+import mx.core.mx_internal;
+import mx.events.PropertyChangeEvent;
+import mx.events.ResizeEvent;
+    
 import spark.components.supportClasses.ScrollBar;
 import spark.core.NavigationUnit;
 import spark.core.IViewport;
-import mx.core.ILayoutElement;
-import mx.events.PropertyChangeEvent;
-import mx.events.ResizeEvent;
+
+use namespace mx_internal;
 
 //--------------------------------------
 //  Other metadata

     *  @playerversion AIR 1.5
     *  @productversion Flex 4
     */
    override protected function viewportHorizontalScrollPositionChangeHandler(event:PropertyChangeEvent):void
    {
        if (viewport)
            value = viewport.horizontalScrollPosition;

     *  @playerversion AIR 1.5
     *  @productversion Flex 4
     */
    override mx_internal function viewportResizeHandler(event:ResizeEvent):void
    {
        if (viewport)
        {
