Threads in c# windows application

Windows Task Manager show开发者_StackOverflows four threads for my simple C# Windows application. What are these for?

1. Main thread
2. Debugger thread
3. Finalizer thread
4. GDI+ rendering thread

Source

There's good discussion on the topic on this thread:

http://bytes.com/topic/c-sharp/answers/588402-do-nothing-winform-app-using-4-threads