, and of what type the editor must be:
observer_widget->setPreferredPropertyEditorDockArea(Qt::RightDockWidgetArea);
observer_widget->setPreferredPropertyEditorType(ObjectPropertyBrowser::TreeBrowser);

// After the observer widget was initialized we can access the property editor and call functions on it:
if (observer_widget->propertyBrowser()) {
  QStringList filter_list;
  filter_list << "QObject";
  observer_widget->propertyBrowser()->setFilterList(filter_list);
}
\endcode

These additions will result i