function openCentered (url, windowName, width, height, featureString)
{
  if (!windowName) windowName = '';
  
  if (!featureString)
    featureString = '';
  else
    featureString = ',' + featureString;
  
  var x = Math.round((screen.availWidth - width) / 2);
  var y = Math.round((screen.availHeight - height) / 2);
  featureString = 'left=' + x + ',top=' + y + ',width=' + width + ',height=' + height + featureString;
  
  return open (url, windowName, featureString);
}

function openMaximised(url, windowName, featureString)
{
	var w = screen.width;
	var h = screen.height;
	var winHandle;
	
	if (!windowName) windowName = '';
	if (!featureString) featureString = '';
	
    featureString = 'screenX=0,screenY=0,left=0,top=0,width=' + w + ',height=' + h + ',' + featureString;
	
	winHandle = open(url, windowName, featureString);
	
	winHandle.moveTo(0, 0);
	winHandle.resizeTo(window.screen.availWidth, window.screen.availHeight)
	
//	return winHandle;
}

function openMinimised(url, windowName)
{
	var winHandle;
	
	if (!windowName) windowName = '';
	
    featureString = 'screenX=0,screenY=0,left=0,top=0,width=0,height=0';
	
	open(url, windowName, featureString);
}