What is the double box figure in the top right corner of the panel?

What is the "double box" figure in the top right corner of the panel ?

"Copy" is what it looks like

When I click it, it says file operation progress with one file operation in progress.

There is another window on the left side small window that is expandable and empty?.

I will check mate system monitor and see if there are another explained processes.

I have been working for a few hour on a backup script that uses rsync and tar.

Some of the "rsync commands" has some mistakes which probably left some open files etc.

Those boxes went away on a re-login.

After using zip files for years, I was told that it does not retain file permissions.

Now I use tar files.

I replaced all cp statements with rsync even though may be some slight speed difference.