The ban on downloading this file does not work.
The list of prohibited extensions to view includes:
pdf,xls,doc,c,zip,rar,7z,tar
but guests can still download .zip archives.
I tried it in different ways - both ways.
But download the archive is still available.
You can hide composer (red button with +) and chat (user avatar as a button) windows by clicking on their respective buttons in the bottom right corner of the screen. Click again to show window and see your own content.
Try to browse forums when composer is opened. This is one more possible action to do.