gtk_tree_model_sort_real_unref_node and gtk_tree_model_filter_real_unref node critical

[Nicolas Soubeiran <nicolas soubeiran gmail com>]

Hello all,
I debug an old code with a treeview that display a "sorted filtered"
list : i.e the model displayed is a GtkTreeModelSort whose child is a
GtkTreeModelFilter whose child is a GtkListStore.

An analogy can be a file explorer that can be sorted and where user
can toggle "show/hide hidden file"
Sometime when the model is actually sort _and_ filtered I have on
selection 2 Gtk-Critical on gtk_tree_model_sort_real_unref_node and
gtk_tree_model_filter_real_unref node : assertion elt->ref_count > 0
failed
This does not happen if the model is either sort or filter.
Both model are using functions to sort/filter.
In the code, some GtkTreeRowReference (on every model) are kept on
"important" rows.
I do not reproduce this bug when I try to made a simple example.

What these errors mean ?
Does anyone has an idea on how I could track this (breaking at the
function that send the error does not help, valgrind and insure++ does
not found any leaks).