Add screenshot of regions to theme page

I'm not sure I know what you mean by that. :-) Yes, those are the regions. They're the same as with Claro, only a little bit more compact.

Most of the documentation on Drupal modules, themes etc. are not very user friendly. (And don't get me wrong: I really appreciate all the free time people spend on developing drupal.)
But 90% of all the modules or themes need to be installed, enabled, checked out and if they do not apply they have to be uninstalled and removed - while simple screenshots could answer many questions and save everyone some time.
So I am trying to help improve that.

If a theme does not provide regions that are required for someones use case. The screenshot would simply help save someone time.

I can see your point but in this particular case, this is cleary something I don't intend to do. This is not a new theme that needs visual description. This is a modification of the default admin theme, bundled with Drupal, available to each and every admin, that only intends to modify spacing and doesn't even touch the positioning and layout of the regions.