OverWorld code

        var vx:int = 0;
        var vy:int = 0;
        var rightInnerBoundary:uint;
        var leftInnerBoundary:uint;
        var topInnerBoundary:uint;
        var bottomInnerBoundary:uint;
        var gravity:Number = 0.3;


    if(!stage){
        this.addEventListener(Event.ADDED_TO_STAGE, stageReady);
    }else{
        stageReady();
    }


    function stageReady(event:Event = null):void {
    stage.addEventListener(KeyboardEvent.KEY_DOWN, keyDownHandler);
    stage.addEventListener(KeyboardEvent.KEY_UP, keyUpHandler);
    stage.addEventListener(Event.ENTER_FRAME, enterFrameHandler);

             rightInnerBoundary
                = (stage.stageWidth /2) + (stage.stageWidth /4);
             leftInnerBoundary
                = (stage.stageWidth /2) - (stage.stageWidth /4);
            topInnerBoundary
                = (stage.stageWidth /2) - (stage.stageWidth /4);
             bottomInnerBoundary
                = (stage.stageWidth /2) + (stage.stageWidth /4);

   }



                function keyDownHandler(event: KeyboardEvent): void
                    {

                    if (event.keyCode == Keyboard.LEFT)
                        {
                        vx = -5;
                        character.gotoAndPlay("WALKL");
                    } else if (event.keyCode == Keyboard.RIGHT)
                    {
                        vx = 5;
                        character.gotoAndPlay("WALKR");
                    }else if (event.keyCode == Keyboard.UP)
                    {
                        vy = -5;
                        character.gotoAndPlay("WALKR");
                        character.gravity = 0;
                    }else if (event.keyCode == Keyboard.DOWN)
                    {
                        vy = 5;
                        character.gotoAndPlay("WALKL");
                    }

                }
                function keyUpHandler(event: KeyboardEvent): void
                {

                     if (event.keyCode == Keyboard.LEFT)
                         {
                        vx = 0;
                        character.gotoAndStop("IDLEL");
                         character.gravity = 0.3;
                    } if (event.keyCode == Keyboard.RIGHT)
                    {
                        vx = 0;
                        character.gotoAndStop("IDLER");
                        character.gravity = 0.3;
                       }
                     if (event.keyCode == Keyboard.UP)
                         {
                        vy = 0;
                        character.gotoAndStop("IDLER");
                        character.gravity = 0.3;

                    } if (event.keyCode == Keyboard.DOWN)
                    {
                        vy = 0;
                        character.gotoAndStop("IDLER");
                        character.gravity = 0.3;
                       }
                    }

                        function enterFrameHandler(event: Event): void

                            {
                                import Collision
                                character.x += vx;
                                character.x += vy;
                                Collision.block(character, boundary);

                                if (character.x < leftInnerBoundary)
                                    {
                                    character.x = leftInnerBoundary;
                                    background.x -= vx;



                                } if (character.x + 90 > rightInnerBoundary)
                                {
                                    character.x = rightInnerBoundary - 90;
                                    background.x -= vx;

                                } if (character.y < topInnerBoundary)
                                    {
                                    character.y = topInnerBoundary;
                                    background.y -= vy;



                                } if (character.y + 90 > bottomInnerBoundary)
                                {
                                    character.y = bottomInnerBoundary - 90;
                                    background.y -= vy;
                                }

                                    if (background.x > 0)

                                    {
                                        background.x = 0;

                                    }

                                    if (background.y > 0)

                                    {
                                        background.y = 0;

                                    }

                                    if (background.x < stage.stageWidth - background.width)

                                    {
                                        background.x = stage.stageWidth - background.width;
                                        }

                                     if (background.y < stage.stageHeight - background.height)

                                    {
                                        background.y = stage.stageHeight - background.height;
                                        }

                            }
                        }