gtk_tree_view_expand_to_path is passed a treeview and a path variable.  A new TreePath, temp is declared to be used as a temporary path for 
expanding the parents of the function's arguement, path.  The function, however, ignores temp, and performs all of it's operations on the 
function arguement, finally freeing it before returning.  Not only will the tree not be expanded properly, but the program will segfault 
when the program tries to free the path that was passed to the function.

the function looks like this:

void
gtk_tree_view_expand_to_path (GtkTreeView *tree_view,
                  GtkTreePath *path)
{
  gint i, depth;
  gint *indices;
  GtkTreePath *tmp;

  g_return_if_fail (GTK_IS_TREE_VIEW (tree_view));
  g_return_if_fail (path != NULL);

  depth = gtk_tree_path_get_depth (path);
  indices = gtk_tree_path_get_indices (path);

  tmp = gtk_tree_path_new ();
  g_return_if_fail (tmp != NULL);

  for (i = 0; i < depth; i++)
    {
      gtk_tree_path_append_index (path, indices[i]);
      gtk_tree_view_expand_row (tree_view, path, FALSE);
    }

  gtk_tree_path_free (path);
}

/*********************************************************/
but should be modified so the for loop looks like this:

  for (i = 0; i < depth; i++)
    {
      gtk_tree_path_append_index (tmp, indices[i]);
      gtk_tree_view_expand_row (tree_view, tmp, FALSE);
    }

  gtk_tree_path_free (tmp);
}