Thread Safe Singleton

Typical WinForms applications are typically running in the UI thread, so the simple singleton will provide you with the functionality that you're looking for. However, if you are creating a multi-threaded application that needs to access a singleton across all of its threads, then you will need to create a thread-safe singleton class instead. What you gain in functionality comes at the cost of some performance, so you shouldn't use this form of the class unless you actually intend to use the class from multiple threads.

Thread Safe Singleton Code