Hi Stefano,
We regret for the inconvenience caused.
Currently we do not provide support for "Event that fires when loading of all elements gets completed” inside Listbox control.
We have created a new incident for this query. And the incident link is given below:
www.syncfusion.com/support/directtrac/incidents/135390
Please follow up in the above incident for further assistance.
Please let us know if you have any other concerns.
Regards,
Rajaveni