Visual Studio has a sidebar that's grey for untouched lines. On lines that you edit, this sidebar turns yellow, and it turns green when you save and red for errors.
Yeah, I thought about something like that (assuming I know what you mean), but since this is about parts of lines, not lines, I thought underlining would work better (especially since basically every line has keywords).
It's still a little difficult to indicate the minibuffer background, the frame border, etc, but I think those names are a little more obvious, and there's fewer of them.
It's still a little difficult to indicate the minibuffer background, the frame border, etc, but I think those names are a little more obvious, and there's fewer of them.