use Tk;
$mw=tkinit;
$mw->Button(-text => "Doit!",
	    -command => sub {
		$t = $mw->Toplevel;
		$t->Button(-text => "Hello!", -command => sub { die })->pack;
		$t->update;
		$t->Busy(-recurse => 1, -cursor => 'watch');
		$t->after(2000);
		$t->destroy;
	    })->pack;
MainLoop;