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Asked: 2026-05-14T00:39:04+00:00

Solution: if you have the same problem, addElement() instead of addChild() is what did

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Solution:

if you have the same problem, addElement() instead of addChild() is what did it

I’m trying to move away from mxml to actionsctipt. I have a <s:Rect> that I’ve created and set its properties, but having trouble adding it. 

var aRect:Rect = new Rect();
//set properties like aRect.x, aRect.y, aRect.width, aRect.height

//tried adding it various ways
addChild(aRect);
Application.addChild(aRect);
Application.application.addChild(aRect);
stage.addChild(aRect);

But I keep getting the error
1067: Implicit coercion of a value of type spark.primitives:Rect to an unrelated type flash.display:DisplayObject

Originally in the mxml, it was right inside <s:Application> not nested inside anything

<s:Application>

    <s:Rect id="aRect" x="10" y="10" width="15%" height="15%">
         //then fill code here, removed for readability
    </s:Rect>

</s:Application>

What’s the deal, I thought actionscript would be nicer than mxml.

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1 Answer

  1. Editorial Team

    It’s because Flex 4 significantly changed the way the display hierarchy works in MXML-based applications. This is a bit confusing since addChild() no longer works as simply as you’d want it to – you have to add elements to a dataprovider, and then the logic of displaying those elements (which ones to add where, how to skin them, etc) is handled elsewhere. It’s kind of a useful change, though, because it forces you separate your concerns in a very concrete way. Once you have your elements all added to your dataProvider you can swap out Layout objects at will (even at runtime) to change the way your application looks.

    EDIT: Technically it’s not the displayList itself that they’ve changed. It’s the fact that the basic unit used by Flex is now the “Group” – even s:Application extends group. You add your content to a a Group (or to the top level Application) and then you assign the group a layout to tell it how to display the items you’ve added.

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