function PopWin (url, width, height, windowName, featureString) {
	if (!windowName)
    		windowName = '';
  	if (!featureString)
    		featureString = '';
  	else
    		featureString = ',' + featureString;
  		var x = Math.round((screen.availWidth - width) / 2);
  		var y = 0;//Math.round((screen.availHeight - height) / 2);
  		featureString = 'left=' + x + ',top=' + y + ',width=' + width + ',height=' + height + featureString; 
	open (url, windowName, featureString);

}