I'd really like to see some imrovements to the in-calculator program editor.

[webmasterpdx]

vi does all of those things except for the function folding...vim contains that function, but it's a big version of vi. With the small version (old version), you can yank chunks of code into buffers quickly and restore them again when you need them. You can also write macros that would allow you to fold functions....I think :-)
When I say vi, I mean something with similar functionality....not exactly vi. The reason I suggest vi is because it fits in a small space and has a huge amount of power. Also some of the functions in vi could be made available to be called from programs, like regular expressions to parse strings.....you could write a program that could change 3 nthroot x to x^(1/3) and the like.

I doubt if this would happen though, but for sure, the program editor does need a rethink.