>you can have Tk (as long as your Cobol allows you to call C).
No C required, you can just connect to the UI through a socket and often skip the FFI completely. This is my preferred way to use Tk and I don't even consider anything else unless there is a reason. Working this way also has the nice side effect of making the application UI agnostic.
Believe you have to do that anyways unless you are going to create full language bindings as tkinter and the like do. I don't know the Tk API in full but I don't believe it provides ways to create widgets, just interact with them more directly. Perhaps someone more knowledgeable will fill in the gaps here, I learned what I needed of the Tk API and called it good.
No C required, you can just connect to the UI through a socket and often skip the FFI completely. This is my preferred way to use Tk and I don't even consider anything else unless there is a reason. Working this way also has the nice side effect of making the application UI agnostic.