Edit Files from Panel

I’m a Panel newbie, so forgive me if the answer is right under my nose and I just don’t see it.

I got stuck with a simple problem: say in a page folder there are several files, some of them text files (for custom purposes).
Opening the Panel’s default view on that folder, I can see these files in the Files section in the right hand column. Clicking on one of those items I get a (default) view that tells me “This file has no blueprint yet. You can define the setup in /site/blueprints/files/default.yml”.

If all I want to do is opening that file for text-editing (like the text editing section in left hand side of the previous page), do I have to create a blueprint? Is there an example for this kind of thing? Or is there possibly an easier way?

With the files blueprint, you can add metadata to a media file, not edit it. There is no out-of-the-box way to edit text files via the Panel, this would require a custom implementation (custom section or Panel area)