c#pinvoke windows-explorer file-transfer

C#: take control over file transfers*

I'd like to have a program that runs in the background, listens for any file transfers, and then cancels explorer's file transfer mechanism, and starts it's own.

How do I do this? Is there some dll that I can pinvoke?

Why?

To filter files of certain types along the way. (automatically, or with a prompt.)
A "no to all" duplicate transfers option.
Logging.
To not have to start the program up every time I want to transfer files.
To further understand what's going on under the hood.
To not rely on third party programs.
Any additional features I think of in the future.

* By file transfers I mean moving/copying files/folders via drag and drop, but I am only concerned with file transfers from disk to disk, not from the internet.

Solution

Define "file transfer".

Do you want to sniff for ftp, http requests? Explorer copies as well? Local only or on the network?

I think this is bound to get brittle. Your best bet would be if explorer let's you hook into file copy operations via a shell extension. I'm not sure whether it can be done.

See The Complete Idiot's Guide to Writing Shell Extensions for a starting point.