IMO the actual problem of "pixel" gui in text mode is simple - how to represent widgets and dialogs, originally designed for "real" pixels, in environment where 1 pixel == 1 character.

E.g. think about all those Frames in EditFields.

Therefore I am afraid that text mode GUI would require heavy adjustment to everything -> it is perhaps easier to design it from scratch (not to use CtrlLib). OTOH, Ctrl itself has perhaps suitable interface....

#include <TuiLib/TuiLib.h>

using namespace Upp;
using namespace Upp::Tui;

CONSOLE_APP_MAIN
{
    Session session;
    PromptOK(session, t_("Hello, world."));
}