FYI The classical Borland text user inteface (TUI) framework used in Turbo Pascal and other terminal MS-DOS editors is open source.
Turbo Vision: https://github.com/magiblot/tvision
Turbo Vision: https://github.com/magiblot/tvision
is there one of those anybody knows about? I have the source to a turbo pascal BRIDGE.PAS card game player I used to enjoy playing. (it's not a good bridge player and it has a scoring bug, but I know how to fix it, and I can run it in dosbox if I want so I'm not desperate in that sense, but I'd rather run native)
Regardless of the history, the API is basically the same, you can even read a tutorial written for Turbo Vision and apply it to Free Pascal with minimal changes.
Recently there has been a UTF-8 version (original TP -and FV- was made for 8bit DOS character codes) though it is a big buggy and slower than the non-UTF-8 version. I tried to use to make an Info viewer[0] some months ago but i had to switch to the non-UTF-8 version due to the bugs.