function clear_field(field){
	if (field.value==field.defaultValue)
		field.value='';
}

function isEmailAddress(theElement)
{
	var s = theElement.value;
	var filter=/^[A-Za-z][A-Za-z0-9_.-]*@[A-Za-z0-9_.-]+\.[A-Za-z0-9_.]+[A-za-z]$/;
	
	if (s.length == 0 ){
		alert("O e-mail deve ser informado"); 
		return false;
	}
	
	if (filter.test(s)){
		return true;
	}else{
		alert("e-mail inválido!" + theElement.value);	
		return false;
	}
}

function assinarBoletim(){
	if (isEmailAddress(document.getElementById('email_boletim'))){
		xajax_assinarBoletim(xajax.getFormValues("formBoletim"));
	}	
}

function removerNews(){
	if (isEmailAddress(document.getElementById('email_remove'))){
		xajax_removerNews(xajax.getFormValues("formRemoveBoletim"));
	}
}

function mostrarMensagem(){
	displayStaticMessage(document.getElementById('mensagem-boletim').innerHTML,300,200,'');
}