function PopUp()
{
	this.overlayId="overlay";
	this.showOverlay=function()
	{
		var obj=document.createElement("div");
		obj.setAttribute("id",this.overlayId);
		obj.style.display="block";
		globalBody.appendChild(obj);
	}
	this.hideOverlay=function()
	{
		if(!document.getElementById(this.overlayId)){return false;}
		var obj=document.getElementById(this.overlayId);
		globalBody.removeChild(obj);
	}
}