flex中，带最小化，最大化，关闭的Panel

package
{
import mx.containers.Panel;
import mx.controls.Button;
import flash.events.Event;
import mx.events.FlexEvent;
import flash.events.MouseEvent;
import mx.controls.Alert;
/**
* This class is used to create a Custom Panel
* with Maximum, Minimum, close
* and also drag properties.
*/
[Event( name="min",type="mx.events.FlexEvent" )]
[Event( name="max",type="mx.events.FlexEvent" )]
[Event( name="close",type="mx.events.FlexEvent" )]
/**
*
* @author Administrator
*
*/
public class DPanel extends Panel
{
//--------------------------------------
// Styles
//--------------------------------------
[Embed( source="/assets/close_over.gif" )]
public static const closeOverIco:Class;
[Embed( source="/assets/close.gif" )]
public static const closeIco:Class;
[Embed( source="/assets/max.gif" )]
public static const maxIco:Class;
[Embed( source="/assets/max_over.gif" )]
public static const maxOverIco:Class;
[Embed( source="/assets/min1.gif" )]
public static const max1Ico:Class;
[Embed( source="/assets/min1_over.gif" )]
public static const max1OverIco:Class;
[Embed( source="/assets/min.gif" )]
public static const minIco:Class;
[Embed( source="/assets/min_over.gif" )]
public static const minOverIco:Class;
[Embed( source="/assets/min1.gif" )]
public static const min1Ico:Class;
[Embed( source="/assets/min1_over.gif" )]
public static const min1OverIco:Class;
//--------------------------------------------------------------------------
//
// Variables
//
//--------------------------------------------------------------------------
private var _showBtn:Boolean = true;
//define if DPanel is Maximum.
private var isMax:Boolean = false;
//define if DPanel is Minimum.
private var isMin:Boolean = false;
//var buttons
private var minBtn:Button;
private var maxBtn:Button;
private var closeBtn:Button;
//Storage for the panel's old property.
private