Hi,
Okay, I misunderstood the original question. ListView itself doesn't restrict the number of items. Most likely you will need to do that at the model or UI level -- e.g. if you control how the user adds elements, you will need to implement your own limit to prevent them adding a 21st item. (also note that if your model always returned a count of <= 20, the ListView would never try to display more than 20 items)
Regards,
Michael