Call functions in parent(?) from popup window(?)

Question

I'm not sure the terms parent or window in flex 4.
I want to call functions in parent from parent window.
it seems to be hard.
Help me please.
Thanks in advance.
========================== index.mxml ==========================
(root element : <mx:Application> - xmlns:mx="http://www.adobe.com/2006/mxml")
has Main.mxml in it
========================== Main.mxml ==========================
(root element : <s:NavigatorContent> - xmlns:s="library://ns.adobe.com/flex/spark" )
public function functInMain():void
//do something
protected function dataGrid_itemDoubleClickHandler(event:ListEvent):void
var arr:ArrayCollection = event.currentTarget.dataProvider;
var titleWindowInstance:Popup =
  Popup(PopUpManager.createPopUp(this,
   Popup,
   true));    
titleWindowInstance.rowData =  arr.getItemAt(event.rowIndex);
PopUpManager.centerPopUp(titleWindowInstance); 
========================== Popup.mxml ==========================
protected function buttonClickedInpopup():void
Application.application.parentDocument.functInMain(null);//<<- here I want to correct

Answer 1

Thanks.
Your callback function works ok
why calling public functin won't work?
here are neet examples.
index.mxml : front page
SearchEvents.mxml : inside index.mxml
UpdateEvent.mxml : poped up from SearchEvents.mxml
========index.mxml===========
<?xml version="1.0" encoding="utf-8"?>
<mx:Application pageTitle="CA Management"
    xmlns:mx="http://www.adobe.com/2006/mxml"
    xmlns:s="library://ns.adobe.com/flex/spark"
    xmlns:i="test.*"
    width="100%" height="100%" creationComplete="application1_creationCompleteHandler(event)" >
<mx:Script>
  <![CDATA[
   import mx.events.FlexEvent;
   protected function application1_creationCompleteHandler(event:FlexEvent):void
    myViewstack.selectedIndex = 0;
  ]]>
</mx:Script>
<mx:ViewStack width="100%" height="100%" id="myViewstack">
    <s:NavigatorContent id="EventManagement" label="Event Management"><i:SearchEvents x="0" y="0"/></s:NavigatorContent>
</mx:ViewStack>
</mx:Application>
========SearchEvents.mxml=========
<?xml version="1.0" encoding="utf-8"?>
<s:NavigatorContent xmlns:fx="http://ns.adobe.com/mxml/2009"
     xmlns:s="library://ns.adobe.com/flex/spark"
     xmlns:mx="library://ns.adobe.com/flex/mx" 
     x="113" y="163"  
     height="100%" width="750">
<fx:Script>
  <![CDATA[
   import mx.collections.ArrayCollection;
   import mx.controls.Alert;
   import mx.events.FlexEvent;
   import mx.events.ListEvent;
   import mx.managers.PopUpManager;
   import mx.rpc.events.ResultEvent;
   public function parentFunction(param:String):void{
    Alert.show("parent function called with " + param);
   protected function btnSearch_clickHandler(event:MouseEvent):void
    var titleWindowInstance:UpdateEvent =
     UpdateEvent(PopUpManager.createPopUp(this,
      UpdateEvent,
      true));    
    PopUpManager.centerPopUp(titleWindowInstance);
  ]]>
</fx:Script>
<s:Button x="637" y="70" label="Popup" id="btnSearch" click="btnSearch_clickHandler(event)"/>
</s:NavigatorContent>
========UpdateEvent.mxml=====
<?xml version="1.0" encoding="utf-8"?>
<mx:TitleWindow xmlns:fx="http://ns.adobe.com/mxml/2009"
    xmlns:s="library://ns.adobe.com/flex/spark"
    xmlns:mx="library://ns.adobe.com/flex/mx"
    xmlns:incl="incl.*"
    showCloseButton="false"
    title="Update Event" width="432" height="500"
    xmlns:subscription="services.subscription.*"
    xmlns:core="services.core.*"
    horizontalAlign="left" xmlns:vo="vo.*"
    >
<fx:Script>
  <![CDATA[
   import mx.core.Application;
   protected function parentFunctionCall(event:MouseEvent):void
    Application.application.parentFunction("param from popup");
  ]]>
</fx:Script>
<fx:Script>
  <![CDATA[
   import mx.collections.ArrayCollection;
   import mx.controls.Alert;
   import mx.controls.dataGridClasses.DataGridColumn;
   import mx.core.Application;
   import mx.events.FlexEvent;
   import mx.formatters.*;
   import mx.managers.PopUpManager;
   import popup.*;
   [Bindable] public var rowData:Object ;//to get the parent row
  ]]>
</fx:Script>
<s:Button label="parentFunctionCall" id="btnPar" click="parentFunctionCall(event)"/>
</mx:TitleWindow>