how to disable an Gtk::ComboBox item?

["B.Hakvoort" <bart hakvoort be>]

Hi ppl,

As the subject states i'd like to disable certain items in a
Gtk::ComboBox. Since the combobox actually contains a Gtk::TreeModel i
guess the question could also be phrased as: how to disable a certain
row in a tree/list?

Any insights?

Thank in advance!,

plors