function PNPopUp(){
	this.win = null;
}
PNPopUp.prototype.open = function(url, l, t, w, h){
	this.close();
	var sFeatures = 'scrollbars,left='+l+',top='+t+',screenX='+l+',screenY='+t+',width='+w+',height='+h;
	this.win = window.open(url, 'pnpopupwin', sFeatures);
}
PNPopUp.prototype.close = function(){
	if(this.win && !this.win.closed) this.win.close();
	this.win = null;
}
//var popupWindow = new PNPopUp();
//window.onunload = function(){ popupWindow.close();	}