My gut feeling tells me I may have to implement a custom appender to do this. But I'm concerned about the threading issue, since I want the text box to display some message in a real-time manner as the system executes a series of actions.

For example, when user clicks some button on my Winform application, the click event handler calls 2 methods: Act1() and Act2(). So I want when Act1() finishes, the text box on the form displays some...