Código PHP:
import mx.transitions.Tween
circulo._alpha = 0;
cuadrado._alpha = 0;
btn1.onPress = function() {
var Twcir:Tween =new Tween(circulo,"_alpha",null,0,100,2,true)
var Twcua:Tween =new Tween(cuadrado,"_alpha",null,100,0,2,true)
};
btn2.onPress = function() {
var Twcir:Tween =new Tween(circulo,"_alpha",null,100,0,2,true)
var Twcua:Tween =new Tween(cuadrado,"_alpha",null,0,100,2,true)
};