Transparency?

Hello,

I'm not so terribly new to Perl but very new to SDL.  I was fiddling with the following "Hello, World!"-ish code in the SDL manual:

use strict;
use warnings;

use SDL;
use SDLx::App;

my $app = SDLx::App->new( width=> 800, height => 600 );

$app->draw_rect([ $app->width / 4, $app->height / 4,
                  $app->width / 2, $app->height / 2, ],
                  [ 0, 0, 255, 255] );

$app->update();

sleep(5);

and found that changing the alpha portion of the rectangle color (eg fading the rectangle out completely via [0,0,255,0]) had no effect on the rendering of the rectangle.  I did some searching on this and found some old<http://www.velocityreviews.com/forums/t906303-problem-with-alphachannel-with-sdl-xxx-blitting.html> questions<http://markmail.org/message/lqtdvmmjmiryumrw#query:+page:1+mid:q63xng5hz7lpcsbl+state:results> from 4+ years ago, but I'm wondering if there is a simple workaround or an approach that has come about since then.

Thank you for your time,

Jack