function ventana(pagina,ancho,alto) {
PosX = (screen.Width - ancho)/2;
PosY = (screen.Height - alto)/2;
if (!window.vent2||vent2.closed) {
	vent2 = window.open(pagina,'hvuss','toolbar=no,menubar=no,scrollbars=yes,resizable=no,left='+PosX+',top='+PosY+',width='+ancho+',height='+alto+''); }
else { vent2.close(); vent2 = 		window.open(pagina,'hvuss','toolbar=no,menubar=no,scrollbars=yes,resizable=no,left='+PosX+',top='+PosY+',width='+ancho+',height='+alto+'');} } 
	function cerrar() {
	if (window.top.hvuss.vent2&&!window.top.hvuss.vent2.closed) {
	close(window.top.hvuss.vent2.name);
	window.top.hvuss.vent2.close();
	}	
}