a GtkTreePath pointing to the tree node whose children have been reordered
a valid GtkTreeIter pointing to the node whose children have been reordered, or %NULL if the depth of @path is 0
an array of integers mapping the current position of each child to its old position before the re-ordering, i.e. @new_order[newpos] = oldpos
Emits the ::rows-reordered signal on @tree_model.
See [signal@Gtk.TreeModel::rows-reordered].
This should be called by models when their rows have been reordered.