// JavaScript Document
function popupBig(url){ 
	var leftCentro = (screen.width-500)/2;
	var topCentro =  (screen.height-480)/2;
	
	window.open(url, 'nombreVentana' ,'scrollbars=0 ,toolbar=0 ,location=0 ,statusbar=0 ,menubar=0 ,resizable=0 ,width=500 ,height=480 ,left='+leftCentro+', top='+topCentro+'')
}
function alterna(url,ancho,alto){ 
	var leftCentro = (screen.width-eval(ancho))/2;
	var topCentro =  (screen.height-eval(alto))/2;
	
	window.open(url, 'nombreVentana' ,'scrollbars=1 ,toolbar=0 ,location=0 ,statusbar=0 ,menubar=0 ,resizable=0 ,width='+ancho+' ,height='+alto+' ,left='+leftCentro+', top='+topCentro+'')
}