This is more like a rough idea, that I haven’t seen in any other editor.
Imagine you have responsive HTML layout, so there are certain elements that needs to be shown just on small bigger devices and there might also be elements just for small devices.
For that you will probably have to implement following CSS classes: “hidden-xs”, “hidden-sm”, “hidden-md”, “hidden-lg”.
What would make code more maintainable, I think, would be an option to batch fold all the code that isn’t for the size of device that I’m developing for at the moment. Let’s say I’m working on the mobile web, than I’d like to have a command, that will fold all the elements having “hidden-xs” class.