$mw->Button(-text => 'Quit', -command => sub { print 'Bye!'; exit; })->pack;

##</code><code>##

    $mw->bind('<KeyRelease-A>' => \&print_something);

##</code><code>##

#!/usr/bin/perl
use warnings;
use strict;
use Tk;

my $mw = MainWindow->new;
$mw->geometry("700x600");

my $canvas = $mw->Canvas->pack(-fill=>'both', -expand=>'both' );
$canvas->CanvasBind("<Button-1>", [ \&print_xy, Ev('x'), Ev('y') ]);

MainLoop;

sub print_xy {
  my ($canv, $x, $y) = @_;
  print "(x,y) = ", $canv->canvasx($x), ", ", $canv->canvasy($y), "\n";
}

##</code><code>##

use Tk::WidgetDump;
use Tk::ObjScanner;

# and later

Tk::ObjScanner::scan_object($the_widget_or_window_to_inspect);