http://www.codeproject.com/KB/combobox/logcontrol.aspx

A Logging Listbox Control

One of the most common questions I hear from programmers who have moved from console-type applications to the GUI world is "How do I use printf to do debug output?" In my first Windows app, a decade ago, I asked myself the same question, and came up with this answer. What I'm showing in this essay and the accompanying code download is the result of a decade of maturing the world's greatest (at least IMNSHO) printf-equivalent. I refer to this in my accompanying essay on the Graphical Developer Environment, but this is the full-blown control with all the features I seem to need.