function Popup( url, windowName, options )
{
	window.open(url,windowName,options);
}
function CenterPopup( url, windowName, width, height )
{
	var options;
	var top = screen.height/2 - height/2-50;
	var left = screen.width/2 - width/2;
	if( top < 0 )
		top = 50;
	options = "top=" + top + ",left=" + left + ",width=" + width + ",height=" + height;
	Popup(url,windowName,options);
}