Just like treeview.
https://bugzilla.gnome.org/show_bug.cgi?id=681005
* @x: (inout): the x coordinate (relative to widget coordinates)
* @y: (inout): the y coordinate (relative to widget coordinates)
* @keyboard_tip: whether this is a keyboard tooltip or not
- * @model: (out) (allow-none): a pointer to receive a #GtkTreeModel or %NULL
+ * @model: (out) (allow-none) (transfer none): a pointer to receive a
+ * #GtkTreeModel or %NULL
* @path: (out) (allow-none): a pointer to receive a #GtkTreePath or %NULL
* @iter: (out) (allow-none): a pointer to receive a #GtkTreeIter or %NULL
*