Hi Kfrajet, thanks for your comment! Well, on my side the question is not to use Processing IDE as a “deluxe” editor like Notpead++ or Atom for CSS and HTML. It’s also not a question of opposing defining HTML elements dynamically vs through HTML code. Both way are interesting and have different advantages. Defining HTML elements into .html file offers the possibility to discover and learn HTML as well as seeing/using interaction between a web graphic user interface and a program inside a simple browser (what most of the web applications we use everyday do). And that offers the opportunity to provide to students better and ‘sexy’ web multimedia user interface (that are often very complete to create in desktop application like a GUI application in Java).
Processing IDE under p5.js should be able to simply edit JS, HTML and CSS files (which are the fundation of the web on client side). It does with JS and HTML but unfortunately it’s not the case with CSS. And apparently it’s simply because a bug, not an intention to prevent Processing users to edit CSS. But it’s a little bit annoying when teaching programming saying to students that for a same exercice or project you have to use another text editor whereas you have already one in the main tool you use. If it’s a bug, it’s certainly a very minor one that could easily corrected. I hope so.