function winpopup(url, win_width, win_height)  {
	sw = screen.width;
	sh = screen.height;

	x = Math.ceil((sw - win_width) / 2);
	y = Math.ceil((sh - win_height) / 2);
	window.open(url, "_blank", "left=" + x + ",top=" + y + "menubar=no,scrollbars=yes,status=yes,resizable=yes,width=" + win_width + ",height=" + win_height);
}