[perl][SDL] Странности.

#!/usr/bin/perl

use strict;
use warnings;

use SDL;
use SDL::App;
use SDL::Event;
use SDL::Color;

our $WIN_W = 640;
our $WIN_H = 480;

our $app = SDL::App->new(
                        -height=>$WIN_H,
                        -width=>$WIN_W,
                        -depth=>32,
                        -title=>'hw'
                        );

sub interface_test {
    my $color = SDL::Color -> new  (
                                    -r=>0x00,
                                    -g=>0x00,
                                    -b=>0x00
                                    );
    my $bgcolor = SDL::Color -> new(
                                    -r=>0xff,
                                    -g=>0xff,
                                    -b=>0xff
                                    );
    my $rect = SDL::Rect -> new(
                                -h=>20,
                                -w=>20,
                                -l=>($WIN_W/2),
                                -t=>($WIN_H/2)
                                );
                                
    $app -> fill(0,$bgcolor);
    $app -> fill($rect,$color);
    $app -> flip;
                                    
    my $event = SDL::Event -> new();
    while (1) {
        while ( $event->poll() ) {
            exit(0) if ( $event->type() == SDL_QUIT )
        }
    }
}

interface_test();

 print $WIN_W;