/* remove windows with no series */
_remempty_winlist(inlist, nowin)
{
        local k, wlist, wstr, tstr;

        if (argc < 2)
        {
                nowin = 0;
        }

        k = 1;
        wlist = "";

        while (1)
        {
                tstr = strget(k, inlist, ",");

                if (strlen(tstr) == 0)
                {
                        break;
                }

                wstr = tstr;

                if (nowin)
                {
                        /* just check window existence */
                        if (castint(wstr) <= numwindows())
                        {
                                wlist += tstr + ",";
                        }
                }
                else
                {
                        /* check empty windows */
                        if (eval(sprintf("isscalar(%s)", tstr)))
                        {
                                wstr = "W" + tstr;
                        }

                        if (eval(sprintf("length(%s)", wstr)) > 0)
                        {
                                wlist += tstr + ",";
                        }
                }

                k++;
        }

        /* remove trailing comma */
        wlist = strextract(wlist, 1, strlen(wlist) - 1);

        return(wlist);
}