[vala] Program segfaults when trying to do anything with treepath of a selected IconView item

[Filip Lamparski <matka poohatka gmail com>]

Hello,

I have an signal handler which activates when an icon in an IconView is
activated. As I understand, such event produces a TreePath object.
The problem is that whenever this signal is fired, the program segfaults.

Here's the code:

[CCode (instance_pos = -1)]
public void on_filter_selected (TreePath filterpath) {
            stderr.printf("Selected filter: %s", filterpath.to_string());
}

Can you tell me how to fix it?

Thanks,
Filip