Further work on SDLRPG

I've redesigned the editor. It's now two different projects, the editor itself and a set of classes for game objects in another assembly. Also, I've switched to using user controls for the tile picker and map editor. Not all the functionality of the original editor is in yet, but it's only a matter of time. Right now, though, I'm focusing on getting autotiles into the class library and the tile picker.

Now here comes the tricky part. I want an unmanaged DLL to handle the actual object classes. That means taking the C# code in the class library assembly and flushing it all out (excepting what the editor needs that the game engine itself doesn't). I'm going to have to look up on unsafe code, PInvoke, and such other .Net voodoo. Anyone know of good resources, articles, etc. on this?