Possible to use Flex Framework/Components without using MXML?

<?xml version="1.0" encoding="utf-8"?>
<custom:ApplicationClass xmlns:custom="components.*"/>

package components {
    import mx.core.Application;
    import mx.events.FlexEvent;
    import flash.events.MouseEvent;
    import mx.controls.Alert;
    import mx.controls.Button;

    public class ApplicationClass extends Application {
        public function ApplicationClass () {
            addEventListener (FlexEvent.CREATION_COMPLETE, handleComplete);
        }
        private function handleComplete( event : FlexEvent ) : void {
            var button : Button = new Button();
            button.label = "My favorite button";
            button.styleName="halo"
            button.addEventListener(MouseEvent.CLICK, handleClick);
            addChild( button );
        }
        private function handleClick(e:MouseEvent):void {
            Alert.show("You clicked on the button!", "Clickity");
        }
    }
}

<?xml version="1.0" encoding="utf-8"?>
<local:MyApplication xmlns:fx="http://ns.adobe.com/mxml/2009" xmlns:local="components.*" />

package components {
    import flash.events.MouseEvent;
    import mx.controls.Alert;
    import mx.events.FlexEvent;
    import spark.components.Application;
    import spark.components.Button;

    public class MyApplication extends Application {
        public function MyApplication() {
              addEventListener(FlexEvent.CREATION_COMPLETE, creationHandler);
        }
        private function creationHandler(e:FlexEvent):void {
            var button : Button = new Button();
            button.label = "My favorite button";
            button.styleName="halo"
            button.addEventListener(MouseEvent.CLICK, handleClick);
            addElement( button );
        }
        private function handleClick(e:MouseEvent):void {
            Alert.show("You clicked it!", "Clickity!");
        }
    }
}

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" creationComplete="onCreationComplete()">
  <mx:Script source="Script.as" />
</mx:Application>

import mx.controls.Button;
import flash.events.MouseEvent;
import mx.controls.Alert;
import mx.core.Application;

private function onCreationComplete() : void {
  var button : Button = new Button();
  button.label = "Click me";
  button.addEventListener(MouseEvent.CLICK, function(e : MouseEvent) : void {
    Alert.show("Clicked");
  });

  Application.application.addChild(button);
}

package {

  import mx.core.Application;


  public class MyFancyApplication extends Application {

    // do whatever you want here

  }

}