Is there a KornShell (ksh) IDE for Windows?
what you need is just an editor with syntax highlighting feature.Personally, I prefer the combination of winscp and notepad2. Configure your winscp to use notepad2 as editor. Then, locate the remote script file in winscp, right click and select Edit. You can now start coding and for every moment you press CTRL+S (save) in your notepad2, winscp will detect and transfer to the server.