dart web toolkit custom open and closed images

Question

What is the recommended way to replace the default open and closed images on a Tree object?

    import 'package:dart_web_toolkit/ui.dart' as ui;
    ui.Tree tree = new ui.Tree();

I took a look at the source of Tree.dart and it looks like the abstract class _TreeResource is supposed to be extended and for this purpose, but it is private.

Answer 1

I have raised issue on github: https://github.com/akserg/dart_web_toolkit/issues/97