var ventana = null;
function nuevaVentana(mipagina,minombre,w,h,scroll,resizable){
posizda = (screen.width) ? (screen.width-w)/2 : 0;
possup = (screen.height) ? (screen.height-h)/2 : 0;
config =
'height='+h+',width='+w+',top='+possup+',left='+posizda+',scrollbars='+scroll+',resizable='+resizable;
ventana = window.open(mipagina,minombre,config)
if(ventana.window.focus){ventana.window.focus();}
}