use Tk;

my $top = MainWindow->new();
$top->bind("<KeyPress>" => [\&click,Ev('K')]);
sub click {
	my ($window, $button) = @_;
	if ($button eq 'Control_L') { # ignore left Ctrl
		print "I don't do anything";
	} else { 
		print $button;
	}
}
MainLoop();