>>> "ESF" == Eric S Fraga <e.fraga@ucl.ac.uk> writes:

> That looks like the fringe.  Do other buffers show this as well?  Check
> the fringe face maybe?

I have to admit but I even don't know what that is supposed to be.
But I run fringe-mode and then selected all. And it is gone. Thanks. 
I learned there exists something whose existence I did not know and
whose functionality I also don't gasp.

Thanks 

-- 
I strongly condemn Hamas atrocities on Israel, especially the despicable pogroms.
I strongly condemn Putin's war of aggression against Ukraine.
I support to deliver weapons to Ukraine's military. 
I support the NATO membership of Ukraine.
I support the EU membership of Ukraine. 
https://addons.thunderbird.net/en-US/thunderbird/addon/gmail-conversation-view/