Checking to see if a Child has been added, before adding

Question

Hey folks,
I'm working on building a gallery, but I've run into a slight snag. The full-size images are not all the same size, so they will overlap when loaded. In the showPicture function, is there a way for it to check to make sure there isn't a full-size image already loaded, and if there is, to remove it before adding the new one? Any help would be appreciated. Thanks!
var imageLoader:Loader;
var xml:XML;
//parse XML data as an array
var xmlList:XMLList;
var xmlLoader:URLLoader = new URLLoader();
xmlLoader.load(new URLRequest("data/gallery.xml"));
xmlLoader.addEventListener(Event.COMPLETE, xmlLoaded);
function xmlLoaded(event:Event):void {
    xml = XML(event.target.data);
    //parse the nodes in the XML file
    xmlList = xml.children();
    //count the number of nodes in the XML file via XMLList
    trace(xmlList.length());
    //loop to load all of the thumbnails, based on the number of nodes in XMLList
    for(var i:int = 0; i < xmlList.length(); i++) {
        imageLoader = new Loader();
        imageLoader.load(new URLRequest(xmlList[i].attribute("thumb")));
        //position thumbs horizontally across stage
        imageLoader.x = i * 110 + 10; //thumbs are 100 x 100 so, +10 to the width, plus +10 from left edge
        imageLoader.y = 10;
        imageLoader.name = xmlList[i].attribute("source");
        addChild(imageLoader);
        //set up thumbs to load primary image on click
        imageLoader.addEventListener(MouseEvent.CLICK, showPicture);
function showPicture(event:MouseEvent):void {
    imageLoader = new Loader();
    imageLoader.load(new URLRequest(event.target.name));
    //position full image below the row of thumbs
    imageLoader.x = 110;
    imageLoader.y = 130;
    addChild(imageLoader);

Answer 1

Oy..I'm an idiot. I realized that all I needed was a second loader to handle the full-size images and simply unload it prior to pulling in the new image. Here's the completed and fixed code:
import flash.display.*;
var imageLoader:Loader;
var fullLoader:Loader = new Loader;
var xml:XML;
//parse XML data as an array
var xmlList:XMLList;
var xmlLoader:URLLoader = new URLLoader();
var imgFrame:MovieClip = new MovieClip();
xmlLoader.load(new URLRequest("data/gallery.xml"));
xmlLoader.addEventListener(Event.COMPLETE, xmlLoaded);
function xmlLoaded(event:Event):void {
    xml = XML(event.target.data);
    //parse the nodes in the XML file
    xmlList = xml.children();
    //count the number of nodes in the XML file via XMLList
    trace(xmlList.length());
    //loop to load all of the thumbnails, based on the number of nodes in XMLList
    for (var i:int = 0; i < xmlList.length(); i++) {
        imageLoader = new Loader();
        imageLoader.load(new URLRequest(xmlList[i].attribute("thumb")));
        //position of thumbs (horizontally across stage)
        imageLoader.x = i * 110 + 10;//thumbs are 100 x 100 so, +10 to the width, plus +10 from left edge
        imageLoader.y = 10;
        imageLoader.name = xmlList[i].attribute("source");
        //add thumbnails to stage
        addChild(imageLoader);
        //set up thumbs to load primary image
        imageLoader.addEventListener(MouseEvent.CLICK, showPicture);
function showPicture(event:MouseEvent):void {
    fullLoader.unload();
    fullLoader.load(new URLRequest(event.target.name));
    //position full image below the row of thumbs and center to stage
    imgFrame.x = (stage.stageWidth - imgFrame.width) * 0.5;
    imgFrame.y = (stage.stageHeight - imgFrame.height) * 0.5 + 130;
    imgFrame.addChild(fullLoader);
    addChild(imgFrame);