I'd second that. Beyond just getting a good code base, it's quite likely that you get some good ideas for APIs and algorithms. Beyond that, Tcl/Tk is a large-i

I'd second that. Beyond just getting a good code base, it's quite likely that you get some good ideas for APIs and algorithms. Beyond that, Tcl/Tk is a large-ish codebase that's still quite manageable, especially considering its age and the many rewrites. For a more idisyncratic view, I once went through Rob Pike's sam editor. No header guards, sparse comments, short variable and function names. But you could still figure out what's going on without any problems. That was the old portable sam, don't know if the current plan9port one is still that good.