how to addressing the MC as a button in AS3

[cancerinform]

You have 2 possibilities.
1. Create a movie with a movieclip in the library and link it to the class ChildSprite.

package
{
    import flash.display.MovieClip;
    public class ChildSprite extends MovieClip
    {
        public function ChildSprite ()
        {
            this.buttonMode = true;
            this.addEventListener("click", onClick);
        }
        private function onClick (obj:Object)
        {
            trace("Hello World");
        }
    }
} 

Then create a document class.

package
{
    import flash.display.MovieClip;
    import ChildSprite;
    public class Example extends MovieClip
    {
        private var myBut:MovieClip;
        public function Example()
        {
            var myBut:ChildSprite = new ChildSprite();
            addChild(myBut);
            myBut.x = 100;
            myBut.y = 100;
        }
    }
} 

In the Document class field in the fla add: Example and test movie.

2. Create a movie with a movieclip in the library and link it to the class ChildSprite_2, which is basically empty.

package
{
    import flash.display.MovieClip;
    public class ChildSprite_2 extends MovieClip
    {
        public function ChildSprite_2 ()
        {
        }
    }
} 

Then create a document class.

package
{
    import flash.display.MovieClip;
    import ChildSprite_2;
    public class Example_2 extends MovieClip
    {
        private var myBut:MovieClip;
        public function Example_2 ()
        {
            var myBut:ChildSprite_2 = new ChildSprite_2 ();
            addChild(myBut);
            myBut.x = 100;
            myBut.y = 100;
            myBut.buttonMode = true;
            myBut.addEventListener("click", onClick);
        }
        private function onClick (obj:Object)
        {
            trace("Hello World");
        }
    }
} 

This last example is closer to the original stage example.

A third possibility is this to mark the movieclip as button.

package
{
    import flash.display.MovieClip;
    public class ChildSprite_2 extends MovieClip
    {
        public function ChildSprite_2 ()
        {
            this.buttonMode = true;
        }
    }
} 

and then an above script as document class without the buttonmode.