What do you mean for "minimize" ? Iconify? If yes, try this:

use strict;
use Tk;

my $mw = new MainWindow;

$mw->Frame(-width=>200, height =>25);

$mw->Button(-text => "Maximize",
        -command => sub {$mw->geometry($mw->screenwidth . "x" . $mw->s
+creenheight . "+0+0")})
        ->pack();

$mw->Button(-text => "Minimize",
        -command => sub {$mw->iconify;})
        ->pack();

$mw->Button(-text => "Close",
        -command => sub {exit;})
        ->pack();

MainLoop;
[download]

You can try perldoc Tk::Wm