Hi Nicolas,
Thanks for your update.
We are able to reproduce the issue at our end. We have fixed the reported issue internally. The changes are included in our latest Vol 3 2015 SP-1 (v13.3.0.12) release which was rolled out. In the latest version, our listbox control is much improved and has more features.
Our latest version is available for downloading under the following link.
Link: Latest Version Location
If you need further assistance, kindly get back to us and we will be happy to help you.
Regards,
Saravanan A J