TreeListModelCreateModelFunc

Prototype of the function called to create new child models when gtk_tree_list_row_set_expanded() is called.

This function can return null to indicate that @item is guaranteed to be a leaf node and will never have children. If it does not have children but may get children later, it should return an empty model that is filled once children arrive.

• param item The item that is being expanded

• return The model tracking the children of