Since the base of the listbox is derived from the MFC version the Sorted property can only be set at design-time. This is the same behavior as the MS version.

The listView control allows you to change the sorting order and so on at runtime.

I guess the only bug here is that the property is not read-only like the MS version. However we added recreation of control on setting this property so listBox is new and you should add items.

Regards,
 Oleksandr Lebed

About listbox Sorted property, the help file says:

Description

Gets or sets a value indicating whether the items in the list box are sorted.

Property type

Read-write property <------

But if we set the Sorted property to True at runtime, the whole listbox will cleared.