A question concerning BackgroundWorker

I've just came across the following phrase on the internet (actually here http://www.albahari.com/threading/part3.aspx#_Using_BackgroundWorker) "code within a RunWorkerCompleted event handler is able to upda开发者_开发技巧te user interface controls without explicit marshaling".

Could anybody explain why doesn't code in this event handler need to be marshalled to main UI thread?

It's marshaled. You just don't have to do any explicit marshaling. That is, you don't have to write the marshaling code yourself. It's done automatically by the BCL code.