+ /**
+ * @return List of group headers. Each list-item consists of the index of the item
+ * that represents the first item of a group and a value represented
+ * as QVariant. The value is shown by an instance of KItemListGroupHeader.
+ * Per default an empty list is returned.
+ */
+ virtual QList<QPair<int, QVariant> > groups() const;
+
+ /**
+ * Expands the item with the index \a index if \a expanded is true.
+ * If \a expanded is false the item will be collapsed.
+ *
+ * Per default no expanding of items is implemented. When implementing
+ * this method it is mandatory to overwrite KItemModelBase::isExpandable()
+ * and KItemListView::supportsExpandableItems() to return true.
+ *
+ * @return True if the operation has been successful.
+ */
+ virtual bool setExpanded(int index, bool expanded);
+
+ /**
+ * @return True if the item with the index \a index is expanded.
+ * Per default no expanding of items is implemented. When implementing
+ * this method it is mandatory to overwrite KItemModelBase::isExpandable()
+ * and KItemListView::supportsExpandableItems() to return true.
+ */
+ virtual bool isExpanded(int index) const;
+
+ /**
+ * @return True if expanding and collapsing of the item with the index \a index
+ * is supported. Per default false is returned.
+ */
+ virtual bool isExpandable(int index) const;
+
+ /**
+ * @return Number of expanded parent items for the item with the given index.
+ * Per default 0 is returned.
+ */
+ virtual int expandedParentsCount(int index) const;
+