Flash builder 4.5 application.application.getchildbyname

Question

Hi,
I came from flex 3 to the newer version flash builder 4.5, so not everything is clear for me..
for example:
I have a project and i dynamically add a custom component on it like this:
var mycanvas:MainCanvas=null;
     mycanvas = new MainCanvas();
     mycanvas.name = "myMainCanvas";
     this.addchild(mycanvas);
i noticed that in the new spark settings addchild no longer is used, so this.addchild would be this.addelement.
fine, by me.. now my problem
later in my program I want to refer to that element.
in flex3 i did:
//maincanvas is my custom component (a canvas with stuff in it like a viewstack)
var myMainCanvas:MainCanvas=null;
myMainCanvas = MainCanvas(Application.application.getChildByName("myMainCanvas");
i now do:
myMainCanvas = MainCanvas(FlexGlobals.topLevelApplication.getChildByName("myMainCanvas"));
this because application.application is no longer supported... also fine by me..
the problem: when i run this.. the program gives an error that myMainCanvas is of a null object reference.
What am i doing wrong here?
The custom component (canvas) i added to the main application is showing on my screen.. so it is definitely loaded..
please some help

Answer 1

Suppose you have a class like the following:
package {
     public class AppModel {
          public var myCanvas:MainCanvas;
Then on your code you could create a instance of that class and set the myCanvas property with the newly created MainCanvas class:
var model:AppModel = new AppModel();
model.myCanvas = new MainCanvas();
From that point on, whenever you need to reference that instance of MainCanvas, you just reference it through the model:
model.myCanvas.width = 100;
If you have to use the myCanvas throughout several classes in the application, it would be better to make it a static property and reference it directly through the class reference. So:
package {
     public class AppModel {
          public static var myCanvas:MainCanvas;
Then:
AppModel.myCanvas = new MainCanvas();
And finally, whenever you need to reference it:
AppModel.mycanvas.width = 100;
Hope this helps. If it does, please signal the thread as answered.
Cheers,
Rui