function mostrardiv(id) {

div = document.getElementById(id);
div.style.display = 'block';

}

function cerrar(id) {

div = document.getElementById(id);

div.style.display = 'none';

}

function abreSinNavegacion(url,w,h){ 
open(url, 'principal', 'location=0, menubar=0, status=0, toolbar=0, width='+w+', height='+h+', scrollbars=1, resizable=1 '); 
}