The latest commit to the cl-gtk2’s git repository adds gtk:tree-lisp-store class. This class implements the GtkTreeModel interface and can be used as a data model for GtkTreeView (gtk:tree-view in cl-gtk2). This is addition for already existing array-list-store that can be used as a list data model for GtkTreeView.

This screenshot shows the working of tree demo (located in gtk-demo:demo-treeview-tree).

The tree-lisp-store API is pretty rough at the moment. For tree manipulation it provides a few DOM-like operations: make-tree-node, tree-node-insert-at, tree-node-remove-node-at, tree-node-children.