Implementation samples of Pluggable MIME Filter (preferably in C#)?

Anyone know of a good sample implementation of a Pluggable MIME Filter for IE, preferably implemented in C#? Or of a pluggable protocol handler?

thanks!

So far I have found

• This SO question with sample code

• this sample: http://www.bsalsa.com/forum/showpost.php?p=3031&postcount=4 (which is briefly documented here) (both from the SO question above)

• This sample from MSFT (but not using C#)

After working with Microsoft support for a couple of weeks, we determined that MIME filters written in .NET do not work correctly. There appear to be a number of thread-safety issues in the interop layers that cause random crashes of IE.

I've reimplemented my MIME filter in C++ following the same sample you linked to above, and it works fine.