Signals the running thread main method to terminate gracefully.
This method is called exactly once; either when the Thread.Stop method is invoked for the first time or when the thread is disposed.
This is the main method of the thread.
If this method throws an exception, the thread is terminated; the exception details can then be obtained via Thread.Error.
This method is invoked regularly when one thread has requested another one to stop and is waiting for its termination.