function NewWindow(mypage, myname, wx, hx, mscroll)
{
var winl = (screen.width-wx)/2;
var wint = (screen.height-hx)/2;
winprops = 'height='+hx+',width='+wx+',top='+wint+',left='+winl+',scrollbars='+mscroll+',resizable=yes';
win = window.open(mypage, myname, winprops);
if (parseInt(navigator.appVersion) >= 4) { win.window.focus(); }
}

function ventana(direccion,nombreVentana,ancho,alto)
{
var posAncho=(screen.width-ancho)/2;
var posAlto=(screen.height-alto)/2;
var atributos='resizable=yes,scrollbars=yes,width='
atributos+=ancho+',height='+alto+',left='+posAncho+',top='+posAlto;
return window.open(direccion,nombreVentana,atributos)
}