var dist:Number = 5;
var keyListener:Object = new Object();

keyListener.onKeyDown = function() {
if (Key.isDown(Key.LEFT)) {
ball_mc._x -= dist;
} else if (Key.isDown(Key.RIGHT)) {
ball_mc._x += dist;
} else if (Key.isDown(Key.UP)) {
ball_mc._y -= dist;
} else if (Key.isDown(Key.DOWN)) {
ball_mc._y += dist;
}
};
Key.addListener(keyListener);