function centrar() {
eje_x=(screen.width-document.body.clientWidth) / 2;
eje_y=(screen.height-document.body.clientHeight) / 2;
moveTo(eje_x,eje_y);
}

function link_popup(enlace) {
      features='width=310,height=122,statusbar=0,menubar=0,toolbar=0,scrollbars=0';
      window.open(enlace.getAttribute('href') + "&id=" + new Date().getTime(), '', features);
}

function checkForm(f){ var message = f.about.value; if(message.length < 2){
alert("You must specify at least a two letters word !");
return false;
} else {
return true;
} }