Textadept is a minimalist multi-platform editor for programmers. It supports syntax highlighting for many languages. Unfortunately, BASIC is not one of them, but support for Nim, Crystal, Pike, Rexx and Icon is pretty impressive. Creating configuration file for any BASIC shouldn't be a problem, though.
https://foicica.com/textadept/
My goal for Script BASIC is to use
IUP to develop the IDE / Debugger and tear apart IupDialogLayout from a single call to an integrated designer for the IDE.
That would be a
code challenge worth participating in.