FLEX4中的datagrid中全选的实现

有位同事是这样实现的 
XML code

<s:GridColumn width="60">  
                                <s:itemRenderer>  
                                    <fx:Component>  
                                        <s:GridItemRenderer>  
                                               
                                            <fx:Script>  
                                                <![CDATA[  
                                                    import mx.controls.Alert;  
                                                      
                                                    protected function checkbox1_changeHandler(event:Event):void  
                                                    {  
                                                        // TODO Auto-generated method stub  
                                                        Alert.show(rowIndex+"");  
                                                          
                                                    }  
                                                ]]>  
                                            </fx:Script>  
                                               
                                            <s:HGroup>  
                                                <s:Label width="10"/>  
                                                <s:CheckBox selected="{this.parentApplication.select}" change="checkbox1_changeHandler(event)"/>  
                                                <s:Label width="10"/>  
                                            </s:HGroup>  
                                        </s:GridItemRenderer>  
                                    </fx:Component>  
                                </s:itemRenderer>  
                                <s:headerRenderer>  
                                    <fx:Component>  
                                        <s:GridItemRenderer>  
  
                                            <fx:Script>  
                                                <![CDATA[  
                                                    import mx.controls.Alert;  
                                                      
                                                    protected function selectAll_clickHandler(event:MouseEvent):void  
                                                    {  
                                                        if(this.parentApplication.select){  
                                                            this.parentApplication.select = false;  
                                                        }else{  
                                                            this.parentApplication.select = true;  
                                                        }  
                                                        //Alert.show(this.parentApplication.DataGrid3.dataProvider.length);  
                                                    }  
                                                ]]>  
                                            </fx:Script>  
  
                                            <s:HGroup>  
                                                <s:Label text="  全选 " paddingTop="5"/>  
                                                <s:CheckBox id="selectAll" click="selectAll_clickHandler(event)"/>  
                                                <s:Label width="10"/>  
                                            </s:HGroup>  
                                        </s:GridItemRenderer>  
                                    </fx:Component>  
                                </s:headerRenderer>  
                            </s:GridColumn>  

其中的this.parentApplication是取<s:Application >标签，this.parentApplication这与<s:Application>耦合度太高，变成其他标签就不能用了，请问如何改为AS,变成组件的形式？具体像这个FLEX3的全选例子形式http://blog.yotuo.net/post/2009/11/DataGrid-CheckBoxColumn.html,注意,我要的是FLEX4！ 
还有是否有FLEX4扩展控件的资料，本人急需！

我了个去!!!