function Bderecho(e) {

            if (navigator.appName == 'Netscape' && (e.which == 3 || e.which == 2)){

            alert('Derechos reservados')

            return false;

            }

            else if (navigator.appName == 'Microsoft Internet Explorer' && (event.button == 2)){

            alert('Derechos reservados')

            }

            }

            document.onmousedown=Bderecho