package {
    import flash.display.Sprite;
    import flash.events.MouseEvent;
    
    [SWF(backgroundColor="#000000", frameRate=60)]
    public class FlashTest extends Sprite {
        public function FlashTest() {
            // write as3 code here..
            stage.addEventListener(MouseEvent.MOUSE_MOVE, createSquare);
        }
        
        public function createSquare(e:MouseEvent):void
        {
            new Square(this, stage.mouseX, stage.mouseY, 128, 128, 3);
        }
    }
}

import flash.display.DisplayObjectContainer;
import flash.display.MovieClip;
import flash.display.Sprite;
import flash.events.Event;

internal class Square extends Sprite {
    private var _root            :DisplayObjectContainer;
    private var _width            :Number;
    private var _height            :Number;
    private var _ttl            :uint;
    private var _life            :uint;
        
    public function Square(root:DisplayObjectContainer, x:Number, y:Number, width:Number, height:Number, ttl:uint) {
        this.x = x;
        this.y = y;
        this._root = root;
        this._width = width;
        this._height = height;
        this._life = 0;
        this._ttl = ttl;
        this.graphics.beginFill(0xFF9900, 1);
        this.graphics.drawRect( -this._width / 2, -this._height / 2, this._width, this._height);
        this.graphics.endFill();
        this._root.addChild(this);
        this.addEventListener(Event.ENTER_FRAME, update);
    }
    
    public function update(e:Event):void
    {
        if (this._life < 4)
        {
            this.graphics.clear();
            this.graphics.beginFill(0xFF9900 - this._life * 0x221100, 1);
            this.graphics.drawRect( -this._width / 2 + this._life, -this._height / 2 + this._life, this._width - this._life, this._height - this._life);
            this.graphics.endFill();
            this._life++;
        }
        else
        {
            this.removeEventListener(Event.ENTER_FRAME, update);
            this._root.removeChild(this);
            if (this._ttl != 0)
            {
                var crtWidth:Number = this._width - 2 * this._life;
                var crtHeight:Number = this._height - 2 * this._life;
                var crtX:Number = this.x - crtWidth / 4;
                var crtY:Number = this.y - crtHeight / 4;
                for (var i:int = 0; i < 2; i++)
                    for (var j:int = 0; j < 2; j++ )
                        new Square(this._root, crtX + j * crtWidth / 2, crtY + i * crtHeight / 2, crtWidth / 2, crtWidth / 2, this._ttl - 1);
                this._ttl--;
            }
        }
    }
}

Split Squares