The correct one is: (defcfun (tree-view-expand-row "gtk_tree_view_expand_row") :boolean (tree-view g-object) (path (g-boxed-foreign tree-path)) (open-all :boolean)) Note the boolean argument.
The correct one is:
(defcfun (tree-view-expand-row "gtk_tree_view_expand_row") :boolean
(tree-view g-object)
(path (g-boxed-foreign tree-path))
(open-all :boolean))
Note the boolean argument.