// ----------------------------------
    // some helpers
    // ----------------------------------
    //

    var popup =  false;
    function dpl_popup (url, wd, ht) {
        var screen_wd   =  screen.availWidth;
        var screen_ht   =  screen.availHeight;
        var pos_x       =  (screen_wd/2) - wd/2;
        var pos_y       =  (screen_ht/2) - ht/2;
        popup           =  open(url,"media","resizable=yes,status=no,toolbar=no,width="+wd+",height="+ht+",left="+pos_x+",top="+pos_y);
        popup.focus();
    }