func : a function or null
data : user data to pass to func
The set_row_separator_func() method sets the row separator function to func, which is used to determine if a row should be drawn as a separator. If func is null, no separators are drawn. This is the default value.
The signature of func is:
def func(model, iter, user_data):
where model is the GtkTreeModel used by the combo box, iter is a GtkTreeIter pointing at a row in model and user_data is data. func returns true if the row is a separator. A common way to implement func is to have a boolean column in model, that indicates if the row is a separator.
See also: get_row_separator_func