Thank you both for the responses! I have gotten closer to my original goal....

use warnings;
use strict;
use Tk;

#declarations
my $char = "@";
my $width = 250;
my $height =250;
my ($xco,$yco);
my @xco =(0..250);
my @yco =(0..250);

my $main=MainWindow->new();
$main->title("No Duplicates");

my $canvas=$main->Canvas(-width  => $width,
                           -height => $height)
                ->pack(-fill => "both",
                -expand => "true");

my $timer=Tk::After->new($main,'100','repeat',\&write);


MainLoop();

# Subroutines
sub write {
    if (@xco && @yco) {
    get_ycoord();
    get_xcoord();
    $canvas->createText($xco,$yco, -anchor => 'center',
                                 -text   => $char,
                    -fill   => 'black');
    }
    else {
    $canvas->createText('120','120',-anchor => 'center',
                -text => 'The end!',
                    -fill => 'blue');
        }            
}

sub get_xcoord () {
    $xco = splice (@xco, int rand @xco, 1);    
}


sub get_ycoord () {
    $yco = splice (@yco, int rand @yco, 1);
}
[download]

Thank you again!!!!!