function derecha(e) {
if (navigator.appName == 'Netscape' && (e.which == 3 || e.which == 2)){
alert('Boton derecho inhabilitado')
return false;
}

else if (navigator.appName == 'Microsoft Internet Explorer' && (event.button == 2)){
alert('Boton derecho inhabilitado')
}
return true;
}


  document.onmousedown=derecha;

  document.oncontextmenu=new Function("return false");
/*
document.onmousedown=derecha*/