How does Invoke work underneath? Doesn't thread have only 1 instruction pointer?

Question

I would like to know how it is possible that C# Invoke function can work (I am now considering the call from worker thread to invoke a method that manipulates GUI from GUI t

Answer 1

It sends a a Window message to the target thread. The thread must be in a message loop for Invoke to work. When the thread gets the message, it calls the delegate.

No cross-thread IP changes are necessary - in fact, changing the IP would almost definitely crash the target thread.