I'm wondering if there is a script already written to make a GUI element that works like this familiar image:

I have an app that I'm developing with Unity that needs a nested folder structure like you see where folders can be expanded/contracted, or clicked on. I have been building a structure in C#, but I hate to re-invent the wheel, and the way I'm doing it just might be a little slow...

Does anyone know if someone has already created a gizmo like the windows folder tool pictured above??

Thank you!!!