Getting the Type Descriptor Provider at runtime

[Edward Beach]

I have a implemented a custom TypeDescriptorProvider /
CustomTypeDescriptor solution for a custom type to display custom
properties when an instances of my custome type is selected by the
PropertyGrid.

To register the TypeDescriptionProvider for my type I use the
TypeDescripionProvider Attribute with my class:

[TypeDescriptionProvider(typeof(MyTypeDescriptionProvider))]

The MyTypeDescriptionProvider maintains a cache of PropertyDescriptors
that I need to refresh every so often so I need to get access to it
after it's been registered. I've tried to call the function

TypeDescriptor.GetProvider(typeof(MyType));

to get at my description provider but instead it gives me a
TypeDescriptionNode. So at runtime how can I get access to my custom
TypeDescriptorProvider?

This question has been asked before but unfortunately not answered
(http://social.msdn.microsoft.com/Forums/en-US/netfxbcl/thread/
0c88ff70-1b9f-4a6b-9977-cc4e70935e87)
Thanks!