insertBefore
Inserts a new row before @sibling. If @sibling is null, then the row will be appended to the end of the list. @iter will be changed to point to this new row. The row will be empty after this function is called. To fill in values, you need to call gtk_list_store_set() or gtk_list_store_set_value().
Parameters
iter
An unset GtkTreeIter
to set to the new row
sibling
A valid GtkTreeIter