Tk itself, does not support transparency, but
Tk::Zinc does. Another alternative is to move up to Gtk2 or Gtk3, which does handle transparency. For example see:
Goo Canvas and transparent images
#!/usr/bin/perl
use warnings;
use strict;
use Tk::Zinc;
my $width = 100;
my $height = 100;
my $mw = MainWindow->new(-background => 'cyan');
$mw->geometry($width.'x'.$height.'+300+300');
$mw->overrideredirect(1);
my $zinc = $mw->Zinc(-width => $width,
-height => $height,
-reshape => 1, #clips zinc
-fullreshape => 1, #clips $mw and xterm
-backcolor => 'cyan',
)->pack;
#make a flower
my $petal = $zinc->add('curve',1,[[$width/2,$height], [0,0, 'c'],
[$width,0, 'c'], [$width/2,$height]],
-tags => ['bezier1'],
-filled => 1,
-fillcolor => 'cyan',
-closed => 1,
-linewidth => 0,
-priority => 1,
-visible => 0,
);
# using the triangulaire curve to reshape both TkZinc and Mainwindow w
+idgets
$zinc->itemconfigure(1, -clip => $petal);
my $petal1 = $zinc->add('curve',1,[[$width/2,$height], [-2*$width,-100
+, 'c'],
[3*$width,-100, 'c'], [$width/2,$hei
+ght]],
-tags => ['bezier1'],
-filled => 1,
-fillcolor => 'cyan',
-closed => 1,
-linewidth => 0,
-priority => 1,
-visible => 1,
);
&Tk::MainLoop;
