window.addEvent('domready', function(){
	$('usuario').addEvent("focus", function(e) {
		e = new Event(e).stop();
		$('usuario').value = '';
	});
	$('password').addEvent("focus", function(e) {
		e = new Event(e).stop();
		$('password').value = '';
	});
	$('codigo_seguridad').addEvent("focus", function(e) {
		e = new Event(e).stop();
		$('codigo_seguridad').value = '';
	});
});