You go back to ace and lose a lot of functionality including the ability to use most ES6 features (it doesn't understand them)
Sorry, but I dont get your point. As far as i can see, it functions like pretty much any multi document editor. In your video, there is highlighted text and the cursor is blinking, and you proceeded to type. It is literally doing what you ask of it.
Here is a demonstration comparing Node-REDs editor to another MDI application - I see no differences (windows 11)
If it is simply a case of the highlight not being clear, chose from one of the many included ones
For example, this is the ACE theme in monaco:
And here is a thread that shows you how to change the theme: How to use themes with Monaco editor
Essetially set codeEditor -> options -> theme to "ace" or "github-dark" or any one of 59 options other themes included
