function openWin(url, win_width, win_height, resize)
{
    w_left = (screen.width - win_width) / 2;
    w_top = (screen.height - win_height) / 2;
    open(url, '_blank', 'left=' + w_left + ',top=' + w_top +
                        ',width=' + win_width + ',height=' + win_height + 
                        ',menubar=no,status=no,scrollbars=yes,resizable=' + resize);
}