function openNewWindow(URLtoOpen, windowName, windowFeatures, myHeight, myWidth) {
  var myLeft = (screen.width-myWidth)/2;
  var myTop = (screen.height-myHeight)/2;
  windowFeatures+=',left='+myLeft+',top='+myTop+',height='+myHeight+',width='+myWidth;

  NewWindow=window.open(URLtoOpen, windowName, windowFeatures);

  NewWindow.focus();
}