function popup(reference,dimx, dimy)
{
	build = true;
	if(window.popup_window)
	{
		if(!popup_window.closed)
		{
			build = false;
			popup_window.location.reload();
			popup_window.focus();
		}
	}

	if(build)
	{
		w = dimx;
		h = dimy;
		l = (screen.width - w)/2;
		t = (screen.height - h)/2;

		popup_window = window.open(reference,'MyPopupWindow',
			'menubar=no,toolbar=no,location=no,directories=no,status=no,scrollbars=yes,top='+t+',left='+l+',width='+w+',height='+h);
	}
}