gtk-tree-store-insert-before (store parent sibling)

store -- a gtk-tree-store object
parent -- a valid gtk-tree-iter iterator, or nil
sibling -- a valid gtk-tree-iter iterator, or nil

Inserts a new row before sibling. If sibling is nil, then the row will be appended to parent's children. If parent and sibling are nil, 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.

The returned iterator point to this new row. The row will be empty after this function is called. To fill in values, you need to call the functions gtk-tree-store-set or gtk-tree-store-set-value.