#!/usr/bin/perl --
use strict;
use warnings;
use Tk;
my $mw = tkinit;
my $target = 45;
my $tmax = 60;
my $bb = $mw->Button( -text => 'JT' )->pack;;
my $tt = $mw->Entry( -textvariable => \$target )->pack;
my $br = $mw->Button( -text => 'RJ' )->pack;;
my $fr = $mw->Scrolled('Frame')->pack;
$fr->Button( -text => $_ )->pack for 0 .. $tmax;
$bb->configure( -command => [ \&dothat, $fr, \$target, $tmax ] );
$br->configure( -command => [ \&dothat, $fr, \$target, $tmax , 'random'] );
MainLoop;
sub dothat {
    my( $fr, $tgr, $tm , $random ) = @_;
    $random and $$tgr = int rand $tm;
    my $tg = $$tgr / $tm;
    $fr->yview( moveto => $tg ); 
    return;
}
__END__