function popup(url, width, height) {
  var params = "";
  params += "innerwidth  = " + width  + ", ";
  params += "innerheight = " + height + ", ";
  params += "width       = " + width  + ", ";
  params += "height      = " + height + ", ";
  params += "dependent   = yes, ";
  params += "location    = no , ";
  params += "menubar     = no , ";
  params += "status      = no , ";
  params += "toolbar     = no , ";
  params += "scrollbars  = yes, ";
  params += "resizable   = yes, ";    
  params += "top         = " + 10 + ", ";
  params += "left        = " + ((screen.width  - width)  / 2);
  var win = window.open(url, "win", params);
  win.focus();
}