function mostrar() {

	obj = document.getElementById('play');

	obj.style.display = (obj.style.display=='none') ? 'block' : 'none';

	document.getElementById('this').innerHTML = (obj.style.display=='none') ? 'Ocultar' : 'Mostrar';

}

function valTexto(text_default, element) {

	value_texto = element.value;

		if (value_texto==text_default) {

		element.value ='';

	}

}