Converts filter_path to a path on the child model of this.
That is, filter_path points to a location in this. The returned path will point to the
same location in the model not being filtered. If filter_path does not point to a location in the child model,
null is returned.
| this |
A `GtkTreeModelFilter` |
| filter_path |
A `GtkTreePath` to convert. |
|
A newly allocated `GtkTreePath` |