var win;
function powiekszenie(url, width, height) {
  win = window.open(url,
										"powiekszenie",
										"toolbar=no,location=no,directories=no," +
										"status=no,menubar=no,scrollbars=no,resizable=yes,"+
										"copyhistory=no,width=" + width + ",height=" + height + 
										",left="+(screen.width-width)/2+",top="+(screen.height-height)/2);
	win.focus();
  }