Editing Marshalling updates to a text box

When you have a text box on a form, it's typically created as part of the form's initialization code, in the main thread.  If you have a background thread that needs to update the text box, you can't just "pass the text box into the thread", nor can you even respond to an Event in the thread with a handler and "just update the text box" (the event handler runs in the thread of the event).

The code isn't difficult to write, but it is ''complex'', in that it's not intuitive nor easy to simply type out when you need it.