function wopen(url, name, w, h) {
    w += 32;
    h += 96;

    var wleft = (screen.width  - w) / 2;
    var wtop  = (screen.height - h) / 2;

    if (wleft < 0) {
        w = screen.width;
        wleft = 0;
    }

    if (wtop < 0) {
        h = screen.height;
        wtop = 0;
    }

    var win = window.open(
        url,
        name,
        'width=' + w + ', height=' + h + ', ' +
        'left=' + wleft + ', top=' + wtop + ', ' +
        'location=no, menubar=no, status=no, toolbar=no, scrollbars=yes, resizable=yes'
    );
    
    win.resizeTo(w, h);
    win.moveTo(wleft, wtop);
    win.focus();
}