Converts sorted_path to a path on the child model of tree_model_sort.
That is, sorted_path points to a location in tree_model_sort. The
returned path will point to the same location in the model not being
sorted. If sorted_path does not point to a location in the child model,
null is returned.
Converts sorted_path to a path on the child model of tree_model_sort. That is, sorted_path points to a location in tree_model_sort. The returned path will point to the same location in the model not being sorted. If sorted_path does not point to a location in the child model, null is returned.