Here's an example:

#!/usr/bin/perl -w
use Tk;
use strict;

my $mw = MainWindow->new;
$mw->packPropagate(0);

 $mw->optionAdd("*Button.Background", "red");

print "ARGV=@ARGV.\n";

my $l1 = $mw->Label(-text =>
    "Application class/name is\n'" . $mw->class . '/' . $mw->name . "'
+");
$l1->pack;
my $b1 = $mw->Button(-background => 'yellow')->pack;
my $b2 = $mw->Button->pack;
my $b3 = $mw->Button('Name' => 'B3')->pack;

foreach ($mw->children) {
    next if ref $_ eq 'Tk::Label';
    $_->configure(-text => "'" . $_->PathName . "'");
}

MainLoop;
[download]

Run this with and without the $mw->optionAdd line to see the effect.

--Bob Niederman, http://bob-n.com