Prepends a new row to @tree_store. If @parent is non-%NULL, then it will prepend
the new row before the first child of @parent, otherwise it will prepend a row
to the top level. @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().
Prepends a new row to @tree_store. If @parent is non-%NULL, then it will prepend the new row before the first child of @parent, otherwise it will prepend a row to the top level. @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().