Steps to Reproduce

<zk>
    <button onClick='desktop.setBookmark("/error/404")' label="test"/>
</zk>

Click the button and see the URL.

Current Result

The bookmark is %2Ferror%2F404

Expected Result

The bookmark is /error/404

Debug Information

According to https://tools.ietf.org/html/rfc3986#section-3.5

fragment = *( pchar / "/" / "?" )

https://github.com/zkoss/zk/blob/v8.6.0/zk/src/archive/web/js/zk/bookmark.js#L43
The encodeURIComponent method was used.

Workaround