I've never heard of showing two different view styles of the same source code document in two separate windows/monitors, but it makes sense. Perhaps this could

I've never heard of showing two different view styles of the same source code document in two separate windows/monitors, but it makes sense. Perhaps this could be done with literate programming, or LaTeX packages (where you use the same file either to build the documentation or install the package), or even Javadoc and its imitators, with an IDE that lets you collapse either the comments or the function bodies. Maybe Light Table could have something like this? But if your tooling had good support for it, like being able to click on a function in the code window and make the doc window bring up that function's info, that'd be pretty nice.