 		 *  @playerversion AIR 2.6
 		 *  @productversion FlexJS 0.0
 		 */
-		public static function center( item:UIBase, relativeTo:UIBase ):void
+		public static function center( item:IUIBase, relativeTo:IUIBase ):void
 		{
 			var xpos:Number = (relativeTo.width - item.width)/2;
 			var ypos:Number = (relativeTo.height - item.height)/2;

		 *  @playerversion AIR 2.6
		 *  @productversion FlexJS 0.0
		 */
		public static function findPopUpHost(start:UIBase):IPopUpHost
		{
			while( start != null && !(start is IPopUpHost) ) {
				start = start.parent as UIBase;
			}
			
			return start as IPopUpHost;

package org.apache.flex.utils
{
	import org.apache.flex.core.IPopUpHost;
    import org.apache.flex.core.IChild;
	import org.apache.flex.core.IUIBase;

	/**
	 *  The UIUtils class is a collection of static functions that provide utility
