function pop2(url,alto,ancho,scroll)
			{
				arriba = (window.screen.height/2)-(alto/2);
				izq = (window.screen.width/2)-(ancho/2);
				window.open(url,'','width='+ancho+',height='+alto+',top='+arriba+',left='+izq+', scrollbars='+scroll+' resizable=no');
			}