function buscar(e)  {
        if(document.getElementById)
                return document.getElementById(e);
        if(document.all)
                return document.all[e];
}

function mostrarOnOffTodos(action) {
        var elem = buscar("tituloMostrarOnOffTodos");
        if (action==1) {
                dis="";
                img="/img/msg_cerrado.png";
                elem.href="javascript:mostrarOnOffTodos( 0);";
                elem.innerHTML = "Ocultar Mensajes";
        }
        else {
                dis="none";
                img="/img/msg_abierto.png";
                elem.href="javascript:mostrarOnOffTodos( 1);";
                elem.innerHTML = "Ampliar Mensajes";
        }
        for (i=1;i<=20;i++) {
                e = "msg_img_" + i;
                if( buscar( e)) {
                        mostrarOnOff( e, action);
                }
        }
}

function mostrarOnOff(eName, action) {
        var elem = buscar(eName)
        if (action == 1) {
                elem.style.display = "inline";
        } else if (action == 0) {
                elem.style.display = "none";
        } else {
                if (elem.style.display == "none"){
                        elem.style.display = "inline";
                        if(window.event)
                                window.event.srcElement.src = "../images_system/msg_cerrado.png";
                        }
                else {
                        elem.style.display = "none";
                        if(window.event)
                                window.event.srcElement.src = "../images_system/msg_abierto.png";
                        }
        }
        // return true;
}


// Escribe un tag <img> con un ancho máximo
function mostrarImagen( src, max_w, alt)  {
        i = new Image();
        i.src = src;
        if( i.width >  max_w)  {
                i.width = max_w;
        }
        sw = i.width;

        document.write('<img src="'+src+'" alt="'+alt+'" width="'+sw+'" align="center">');
}