How exactly to I implement this in C#?

I've created my package and implemented the interface methods in

public class MyToolWindow : ToolWindowPane, IVsUIHierarchy

as stub methods for the moment. Putting Trace writes in these methods
shows me that they never get triggered.

Does anyone have a working example for this?

The background: I want to create my own toolwindow with a Hierarchy
view. I want to be able to drag and drop items from this list into the
Forms designer or editor and then do some things with (mostly)
serialization. My understanding was that a toolwindow with hierarchy
interface should provide this functionality. UNfortunately this seems
to be a complete grey area as searching on Google, MSDN and Online Help
doesn't return anything really helpful. Also running the Data and
Crystal assemblies through reflector didn't open my eyes.

If that's not possible in managed code, does someone have an example in
C++?

Thanks for ANY pointers