Inserts a new row before sibling. If sibling is NULL, then the row will
be appended to parent 's children. If parent and sibling are NULL, then
the row will be appended to the toplevel. If both sibling and parent are
set, then parent must be the parent of sibling. When sibling is set,
parent is optional.
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_tree_store_set() or gtk_tree_store_set_value().
Inserts a new row before sibling. If sibling is NULL, then the row will be appended to parent 's children. If parent and sibling are NULL, then the row will be appended to the toplevel. If both sibling and parent are set, then parent must be the parent of sibling. When sibling is set, parent is optional. 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_tree_store_set() or gtk_tree_store_set_value().