I’m releasing a small C++ library with source code called GLConsole that was very useful in my old college game and research projects. It’s a simple “Quake-style” debugging console/shell you can overlay on your application to expose any program variables for tweaking separately from the code, print error or status information, and/or access custom commands. It also does the standard shell things like complete/partial tab completion with suggestions and history. More details including a demo and the source are available at its project page.