use Tk;

my $mw=new MainWindow;

my $toplevel;

my $toplevel_open=0;

my $status=$mw->Label(-text=>'Toplevel Closed :(')->pack;

sub close_toplevel
{
	return if !$toplevel_open;
	$toplevel->destroy;
	$toplevel_open=0;
	$status->configure(-text=>'Toplevel Closed :(');
}

$mw->Button(-text=>'Open Toplevel',-command=>
	sub {
		($toplevel=$mw->Toplevel())->OnDestroy(\&close_toplevel);
		$toplevel_open=1;
		$status->configure(-text=>'Toplevel Open :)');
	}
)->pack;

$mw->Button(-text=>'Close Toplevel',-command=>\&close_toplevel)->pack;

MainLoop;