title: QListWidget get list of viewed items
body: <p>Let's say I have a listwidget with lots of items. When the user scrolls to see more items, I want to perform an action to the items being viewed. Is it possible to trigger an event itemsViewedChanged(QListWidgetItems *items) that gives me the currently viewed by the user items?</p>
  
  <p>If no, how can I implement something like this?</p>
  
  <p>Thanks for any answers</p>