PtFileSel pre-selecting file

I am using a PtFileSel widget. It essentially works. But what I’d
like to do is to select a specific file from code and open up the tree
to that file as necessary.

I noticed that there is a PtFSSelect() that I can use. I put that
inside a loop that iterates through all of the PtFileSelItem_t s from
from PtFSAllItems(). But if the tree isn’t already open to that file
it won’t get found.

I know I can open and close tree branches as necessary. But it seems
like there should be a convienence function to do this. Is there?

Also, I assume it is my responsibility to free() the buffer allocated
by PtFSAllItems() if it was passed a NULL buffer address?