Basically just the title said. The situation is basically I use a Domain-Specific Language called G’MIC, and to this day, I haven’t found a satisfactory answer to the issue of lack of syntax highlighting. At the moment, I am using KDE Kate as it’s pretty good at structuring the code with their find/replace feature, tab indicators, and multi-window support.
Take a look at Sublime Text. It has pretty solid syntax support plus all the other things you need (tabs, structure, tab ind, multi windows) and I’m pretty sure can pretty easily have a custom highlight config written easily if you’re already comfortable with code.
I can second this. I wrote a syntax highlighter for a DSL in Sublime ages ago and all I remember is that it was easy.
That said, you can definitely do this in VS Code, too (just I haven’t personally tried it). IMO VS Code is the better editor.
VSCode and Sublime use a TextMate-like format and can be converted between the two. I have made language support and recommend VSCode.